GMC Jimmy Fuel System

gator14

My jimmy would run for awhile then stop. Let it sit for awhile then it would start. Changed the fuel pump same thing, changed the relay same thing, changed the ecm same thing. was told to check the oil presure swith but don't know where it is. Dose anyone know (help)

gator14

repairdog

4.3 is back by the distributor on a small pipe so look for the electrical connector. Look at the part online or at a store and see what it looks like then you will spot it. You sure its fuel related and not spark (coil, ign module, etc) as it heats up?

gator14

yep cause if you hot wire the fuel pump and some one pours gas into the TBI it runs great. i figure this is the only thing left to change ( i hope).

gator 14

repairdog

Not sure which motor 4.3 or 2.8 you have or if CPI or the older TBI with the fuel metered into the top of the "carb".
Did you check the ECM (may be 2) and ENG fuses also? CPI needs higher pressure like 60psi to start while TBI is like 12psi.

gator14

Well we got it going. Turned out to be broaken wire from the key to the relay. We just jumped the relay and it works. Thank you all for the help..

Gator 14

97jimmy1

I have a 97 Jimmy that will not build fuel pressure. If you give it starting fluid it will start and run on the starting fluid but then die when you stop feeding it. No pressure at the rail. Other symptoms I have found are that the oil pressure gauge stopped working (Stuck on 20 PSI). The fuel gauge shows just under full and it only has about 1/4 tank. It will not come out of park. All these things worked fine until the fuel issue. I have changed the fuel filter and found that it was pretty well blocked off. I have read that there is a fuel pump run wire under the hood. Is this true? Where would I find it? Any other way to test the pump? I hate to drop the tank and change it out ($300.00) without knowing its bad. Especially since I have the other symptoms. What other types of fuel shutdown safety/security items are on this vehicle (IE. low oil pressure, inertia shutdown)?

repairdog

OK - checked Haynes again and the test wire is red and by the firewall and master cylinder. This bypasses the relay. Check the ECM Bat fuse that powers the relay and switch the fuel pump relay with another thats the same as a test. Also remember that the 97 only has a known ignition switch (actually a module with wiring in the column) failure and it effects most power on the vehicle as it runs thru there when the key is turned.

97jimmy1

Powered the test wire and the pump works fine. Rotated the relays (the 3 in the glove box) and no change. Checked all of the standard fuses and they were fine. Is the ECM Bat fuse located in the regular fuse box by the drivers side door or some where else?

rickvan

I have a 95 GMC Jimmy with 300000 kms on it, I have done the fuel pump, sending unit and have done repairs to the rotted out fuel lines. If it sits for more then 4 hours I have to use starter fluid to get it going. 2 hours it will start 4 hours is touch and go 6 hours forget it. I have been told the fuel lines need to be replaced because it is getting a air pocket in the lines. Any insight in to this situation would be appreciated.

dbouchard

replaced plugs wires cap rotor fuel pump, sending unit, and fuel pressure regulator it has 62 psi key on not running 55 psi when it starts but some times wont start unless you spray starting fluid in intake , gm dealer ran test on spider assembly and said al was good , what should i try next? can anybody help

repairdog

Could be sensor or electrical - any codes set the SES ever? I'd look at the electrical connectors, the crank sensor under the front of the engine by the bottom of the timing cover (tells ECM where timing is off the crank), all wiring/cables from the battery are clean and good (do not like low voltage), then other sensors (MAF, temp, O2 etc)but GM should have scanned the sensors and ECM, then a weak coil so plugs are firing but weak. Finally, when was the cap/rotor new and was it Delco and not a cheap aftermarket one - I fought one for several days that was under a year old and was arching in the plastic (can't see internal casting) so several plugs firing at once - changed and all well. Then also look at the vac lines for rot and replace 5/32 and 7/32" all that are bad. The cam sensor in the dist will not cause a no start only rough idle. Then the ign module in the dist fires the coil, but........Sorry, not a simple answer but again suprised GM didn't see anything. Haynes/Chiltons cover testing most of these with a simple multimeter.

dbouchard

replaced plugs, cap, rotor,good spark at coil and at plugs , no codes, starts up when you shoot it with starting fluid, and will stay running ,try to restart and also starts most of the time but when it dont have to reshoot with starting fluid maybee once a week

pwardon

I have a 1994 Chevrolet S-10 Blazer with a 4.3L Vortec. Came home with no problems. Next morning it would not start. Mechanic cannot determine problem except fuel pump isn't getting power. I had the fuel pump replaced eight months ago. He said to take it to dealer for further diagnosing. Before I do, does anyone have any suggestions or opinions about what could cause the fuel pump not to be getting power? Please help!

97jimmy1

The solution to my original post was the the starter switch (not the key but the switch attached to it). Apparently this is a common issue on the 97s

repairdog

Fuel pump relay or fuses need to be checked and there is a red wire up by the brake booster that can power the pump bypassing all relays etc to test it - shop should know this or ....

tech1help

Did you ever figure out why your 97 Jimmy will not build fuel pressure If not I can help. For starter's can you hear the fuel pump hmmm when you turn the key switch on and off? If so have you checked to see if fuel is flowing at all by depressing the shrader valve back by rear of engine and having someone crank engine. If fuel is flowing or squirts with key on engine off then you have pressure. You need 60 PSI to start the vehicle on a vortex setup. If all the above information is happening then you might want to check you Crank Position Sensor for resistance. If it does not have a signal, your MFI manifold will not fire the fuel injectors. If you Have no pressure at the shrader valve when depressed, with key on engine off then your fuel pressure regulator has gone bad. Hope this helps.

jpilchesky

My 99 Jimmy was working fine in the morning when I came home, and when I went to restart it several hours later it would not start. Ignition turned over, and there definitely was gas in the tank, but I added some anyway, and it still would not start. I replaced the ECM fuse under the hood, and replaced several other fuses related to the fuel pump. No start. I then put gas directly into the carb, and the engine turned over but then died.

From other discussions, I could not find this issue addressed for specifically the 99 Jimmy. It is a 4wd.

Additional incidents that may be related:
The service engine soon light was on for about a week, then was off for about two weeks. It came on again two days before this situation.

The fuel gauge would read accurately until it got to about 1/4 tank, then it would jump to either full, or completely empty. I only ran out of gas one time due to this problem and that was about a year ago. Since that time, I have always kept fuel level high to avoid this and have used my trip odometer to keep me posted on fuel level.

Otherwise, possibly unrelated, the dash lights for the radio and steering wheel are half lit, but recently the lights for the radio are completely dark. The heated seat for the driver's side stopped working during the last two weeks.

repairdog

Could be electrical and you need the code readout to see what tripped it (could be your answer -or not). To test fuel pressure need $35 fuel pressure tester and 60psi key on engine off and running 53psi min. Then could be simple cap/rotor problem so replace those. Next is test coil and ignition module mounted on it (stores test for free). Then crank sensor next. As to the lights could be just burned out and the seats check the fuse under hood for that baby - if the switch or wiring gets rubbed thru that can blow the fuse (your manual tells which is which and so does the inside of the cover). Let us know.

jpilchesky

I replaced the ECM fuse and it didn't start, then I cleaned carefully the ports where you put the fuse into, thinking maybe dirt was in there, replaced the fuse, changed the oil, and then it did start. It worked for two days, and then after sitting overnight in the garage, it wouldn't start. I did put gas directly into carb, and it cranked. What about fuel filter?

repairdog

Yes, under the frame under the drivers side door area - a mess to do but not hard about $15 part. The only way to know about pump is to test the pressure. If pressure OK then its electrical/sensor and change the cap/rotor first, then check coil, and then crank sensor.

jlflemmons

I know this will sound crazy, but give the gas tank a swift kick. I learned this trick from a wrecker driver who said the common failure in the fuel pump was that it would stop at a "dead spot" in the windings. Gave the Yukon a kick in the tank when this same thing happened and bingo, fired right up. Took it to the dealer (warranty) and one of the mechanics admitted that they did the same thing when one came in on the hook and they didn't want to physically push it into the shop for the pump replacement.

countryboy276

Hello,
I am having similar problem with my 98 4x4 Jimmy did you figure out what the problem was?

Thanks
David

jpilchesky

It actually worked for about two weeks, and then shut down again. We've been in snow for that time, so I didn't get to take the advice of repairdog and change the fuel filter. It's sitting in a parking lot, and as soon as I can tow it home (snow is everywhere making it difficult), I'll change the filter and let you know. Sorry can't be of more help right now. It cranks over, and when I put a shot of gas in the carb, it fires right up.

countryboy276

I am in a similar situation with the snow..At least my truck is the house. I changed my fuel filter too and my truck ran good for about a month, then started the same thing again. What diagnostic codes have you received? I get a PO147 which is HO2S Heather circuit bank1, sensor 3. HO2S is Heated Oxygen Sensor. According to some info I found..When the ignition is turned on, battery voltage is supplied to the HO2S heater to provide for faster sensor warm-up,thus allowing sensor to become active in a shorter period of time. When the temperature warms up more I am going to trouble shoot HO2S heater sensor and probably install new O2 sensors since my truck has 160,000 miles on it and they haven't never been changed. Keep in touch since it seems we have about the same problem. We might be able to help each other out by sharing info.

David
countryboy276@insightbb.com

chrissanders

I currently own a 1991 Jimmy, but it has many problems. The jimmy i have now is 2 door, dont know if that matters, I just bought a 1993 4 door Jimmy and the only thing wrong with it is the fuel pump regulator. I was wondering if I could take the fuel pump regulator off of my 91 jimmy and put it on the 1993 jimmy I just bought. If you know the answer please email me at chrissanders91@aol.com

repairdog

Look both years up on the online auto sites and see if the same. I would go new as its the labor thats the pain.

aaron13

Can someone give me some advise on my v6 4.3 Jimmy? my truck will run for a while about 10 or 12 miles I will stop the engine for a few minutes and try to start it again and will not start. Pump will not have electrical power (no noise on the pump). after a few minutes the truck will start again and can hear the pump running again. I have put a new gasoline pump, a new gas filter, a new fuel pump Relay. What else can I try? any sensors any where?

jim102

Hi, Just wondering if you have figured out what the problem is with your Jimmy. I have been having similar problems with mine for the past year and a half. Replaced the fuel pump, and wires. It will sometimes start, sometimes not. There has already been a hole cut in the back of truck so top of pump is exposed where previous owner obviously had problems. I can open the back tap on pump a few times and usually it will start. Sometimes the pump will shut off when I am just driving down the road. I can't seem to find any explanation for why it is just shutting off. Any advice?

repairdog

Airtex makes a replacement connector for the top of the pump that may solve that. Must also have a good ground. Hope the pump put in was a Delco cause many others fail in a year so do a pressure test key on engine off and then running. Min of 60 psi KOEO and then 54 or so running.

slim10

I have 97 s-10 blzr with fuel pump issues. The red test wire mentioned to bypass the relay, is it an open wire with a female spade connector on the end or is it attached to a junction or terminal? Thanks

97jimmy1

jbodden6977

my best considered advice - there are two ways to go on this.
A new stock fuel pump is not one of them.
After much experimentation and diagnosis I believe the fuel pressure regulator is at fault - somehow it is tellin the fuel pump that there is 60 pounds of fuel in the line so the fuel pump does not need to run!!!
A political simile, the CIA report on WMD in Iraq...

I believe the item responsible is inside the throttle body on top of the engine - or maybe Saddam has it so well hidden we can't really prove it exists?

Ha ha ha...

If the vehicle was mine, after installing a new pump and it repeating the same symptoms after four days of running, I would put in a new pickup line (fuel from the tank) eliminating the stock fuel pump, install an inline external fuel pump (on the inside of the frame) with a fuel filter before AND after the fuel pump - (due to the way the fuel filters are a part of the fuel line design on some vehicles removing the second fuel filter is both bothersome and really beside the point).
The pumps such as available on Ebay are about $129, hit up to 120 psi - and are more accessible than dropping the fuel tank every darn time... just my two copper plated zinc pennies worth. Good luck. I am sticking with my 73 Dodge van.

repairdog

The problem with this is the pump and fual gauge are one unit. A new Delco pump and Airtex connector on top fixes most and with all newer vehicles the pump is cooled by the fuel so running down to empty all the time promotes earlier failure by overheating - thats just the facts.

The pressure regulator is part of the injection assembly located under the upper intake manifold plastic cover and under that big electrical connector behind the throttle body.

jim102

Thanks for the advice! No, the pump was not a Delco, I thought I would take the cheap way out and had ordered one off of the internet for half the price of any of the parts places here. Guess you get what you pay for. I will try the replacement connector and check ground, but probably just end up replacing pump with a Delco.

jbodden6977

I have disassembled a stock fuel pump. You can remove ONLY the pump/motor and simply extend the tube that leads to the output nipple so that it picks up fuel from the bottom of the tank (with a screen of course.)
then just replace the plastic pump casing/housing thingie WITH the fuel level sender still intact and in place.
If you look closely you will find that the pump housing is a two piece snap together assembly. Easily separated to access the pump unit.

jbodden6977

I did replace the pump with a new pump. The tank had a full load of fuel for the four days before the fuel pump started the exact symptoms of the 'bad' pump we replaced.
Pardon my impatience, but I am only too aware of the design defect of this modern moronic piece of so called engineering that is designed to fail due to a 'too empty fuel tank'.
this kind of engineering is proof that cousins should never marry - their mothers.
Somehow I seriously doubt that I, and all the many many others with the same results, managed to 'wear out' a new fuel pump in four days. :lemon:

jim102

Maybe a helpful article for anyone with GM vehicle from 1988-2005 fuel pump problems.

www.airtex.com

Many GM vehicles from 1988-2005 have electrical connectors on the fuel pump module that may become loose over time due to vibration, leading to faulty, high-resistance connections. The symptoms- burned or melted connectors and pins- lead to a voltage drop situation where low or no voltage can cause the module to stop pumping.
Solution: Airtex products latest fuel system solution provides a quick and reliable fix for burned or melted wiring harness connections on certain GM in-tank fuel pump applications. Airtex has replaced the faulty OEM design that eliminates the burned or melted connectors and pins problem.

mtlwiz

i know it's probably been beaten to death, but when a fuel pump is going,can it only show up at start up as if it'll run rough untils it seems as if once a few degrees of heat gets in the cylinders then it'll straighten out and run fine? no codes,100,000 miles new pump about 10,000 ago but is progressivly gett more noticeable,almost as if it takes time for fuel system to biuld pressure as its started to drive away then will accelerate normally.

repairdog

Have to test the pressure at the port on the fuel rail to know. Rough could be many things as dirty MAF snesor, fuel filter, air filter, air idle control valve, etc.

jpilchesky

atapia

I have a 95 GMC Jimmy 4dr.2wd. I recently replaced the fuel pump, and noticed two valves on top of the gas tank. One of which had a small crack on the neck of tube which leads to what seems a vaccum or a canister of some type. Tried to purchase one at typical auto parts store and they didn't have it and didn't know what exaclty it was for. Do I have to dealer to get one, do I really need it? Can someone help me with this problem.

mhildreth

have 94 jimmy problem misses at idle, backfire when revved up replaced timing chain and gears ,ign module,plugs,wires cap and rotor yes timing gears are set correctly has new fuel pump filter by prev owner oh yes also new coil jimmy has 174000 mi have run fuel inj cleaner in it the engine will rev with a lot of patience but has no power did check with timing light ok

mhildreth

After replacing and testing alot of items . I finally replaced the fuel injector . Very expensive but fixed the problem. There is only one test to see if its working no way to check the nozzles. To see if they are clogged. Only a few minor bugs to work out so good luck out there. Got to luv bowties!

mhildreth

Have you tried hot wire to fuel pump to see if it works could be bad connection at pump also ground , the relay could have corroded connections. With key on check for power at relay. Have noticed with these vehicles that most of conectios have corossion problems even inside the dash.

jerry57

at the fuel pump at the tank unhook the wires and when i tested for voltage.
one had voltage all the time i assume this is the gas gauge.
because it was low voltage.then you will have two that is the ground.
then the other one don,t have voltage on it with just the switch turned on.
but as soon as you turn the switch on over as to start it it has voltage is this the way it is suppose to work

mom23boys

Can anyone tell me where the fuel pump relay is located on my 97 GMC Jimmy 2WD??? I have tried my Chilton's book - the Chevy House--Autozone!!
I need Help! THANK YOU

ms71171

Ok, bought a 96 GMC Jimmy 2 door for my daughter's first vehicle - Good looking truck, 190K, 4.3

After 1 month the fuel pump failed - no big deal, done this before with the in tank fuel pump on my 99 suburban. Replaced with a Airtex fuel pump from Oreilly Auto Parts and all was good.... For 5 days - broke down again.

Checked the fuel pressure at the fuel rail and fuel squirted everywhere, so I THOUGHT I had fuel pressure... and the truck would run with starting fluid - SOOOO I went down the route of replacing the Fuel Injector Assemby (Spider). This did not fix it. Luckily, I bought a used working one on ebay for $40.

Finally bought a fuel pressure gauge (hind-sight 20/20) and realized I had 12 psi.

Replaced the Fuel Pump with a new one from Oreilly no questions asked.

Getting very good at this at this point - Thought I was good to go - Bad pump I thought.

Week later, after pumping gas, the truck would not start again.

Fuel pump wiring harness? Don't think so since the Airtex came with a new one
Clogged Fuel filter? will check, but doubt it. Already replaced on the first swap.
Cough up the money for the AC Delco? Thinking this may be the fix.
Hitting the truck to free up a stuck pump? Will try this tonight to see if it starts.
Blowing out the fuel lines? Need to do this

Here's my conclusions, based on everything I've gone through.

1. Check fuel pressure - Buy the $50 high pressure gauge kit - worth it! Just because you hear it whinning does not mean anything - You need at least 56 psi.
2. Be ultra careful with the plastic fuel connectors on the lines/pump
3. Be sure to keep your little fuel line plastic clippy things if you're returning your pump

I'll update tomorrow after I troubleshoot this second failed fuel pump.

etubbs

i got 97 jimmy its on back the motor close to the dashright down ull see it sticken out of the motor right under the distributer thats where mine is ..........ed

wgrace

My oldest daughter acquired a '01 Jimmy 2wd. Everything fine and dandy until it wouldn't start. She is 26 (and knows everything) and takes it back to dealer to fix. Dealer has new fuel pump and filter replaced and not too happy that he has to spend $600+ to keep her happy. One week later, same thing, wont start. She goes back to dealer to find that the dealer and his mechanic hasn't got a idea what to do. Now nobody is happy. She ask me for help, I hit the tank w/a big wrench, fired right up. Did the same thing several times over the course of a month, then it finally just wouldn't start at all. After month and a half as a yard ornament she asked if I would like to buy it cheap, big hearted me I said yes. Gave her the money and towed it home. Spent today trouble-shooting the fuel system and found the fuel pump ground wire loose(black wire w/white runner). As soon as I repaired the ground, it fired right up. If you don't see another post from me, then you'll know it worked. Oh, by the way, I've got 12 years w/ John Deere, Caterpillar, and big trucks.

ms71171

Just wanted to update everyone on what finally fixed my 96 Jimmy's fuel pump. I ended up replacing the fuel pump 3 times. 2 times with the Airtex brand from Oreilly Autp Parts, and the last with a OEM Delphi fuel pump. Using the OEM fuel pump is critical it seems on these Vortex motors which seem to be very sensitive to fuel pressure.

The second Airtex fuel pump never completely quit and would keep the truck running just fine if I started it with some fuel dumped in, but never made more than 50psi which is not enough to start the 4.3. It needs at least 54psi to start.

My advice would be to pay the extra $30-40 bucks for the OEM Delphi or AC Delco fuel pump. Don't waste your time on other brands - You only want to do it once, right?

97jimmy4dr

Just got the truck a week ago, has fuel leak(driver side) drips off of frame when engine is running,only when running. Anyone have any ideas what I should look for, before I go under to have a look????