99 GMC Safari Stumbling

[littledh173]

I have a 99 GMC Safari that has been giving me some wierd problems as of late. It started early Friday morning when I was on my way to town when it started acting like it was running out of gas but slowly. It never would die out but it keep getting weaker and loosing power. The longer I drove the less speed I was able to maintain. I stopped and topped off my gas tank ( had 1/2 when this started) and afterwards it ran good but the symptoms returned. Evertime it was stumbling real bad it would set the P0131 code for lean condition for HO2O sensor on Sensor 1 Bank 1. It didn't matter how long I turned the engine off it would always run better when re-started, just not very long.

I have read many topics that are close but not the same as my issues and I was hoping someone would have a direction for me as I am on a very short time frame before I have to have this completed. Thanks in advance.

[dunedog]

I would start with a new fuel filter.

[ScottS]

Deinately do the filter , also check the harness that supplies power to the fuel pump, there are bad connectors out there , Airtex has a replacement harness

The bad connectr wil heat up and create more resistance which reduces the voltage to the pump as it gets hot.I have seen ,melted connectors. just not sure if this was a 99 problem or what - I willl look on the Airtex site

[ScottS]

here you go- http://www.airtexproducts.com/TSB/TSB-1106-02_ATX.pdf

[littledh173]

I just finished installing another fuel filter with no changes. When I installed the new fuel pump it came with a new plug which I installed. Thanks for thw quick replies.

Has anyone paid to get answers from the site justanswer.com and was it worth it?

[ihatemybike]

I've never paid for van answers. Between ASV, S10 forums, and asking questions of the mechanics at the local dealer my questions get answered for free. Usually a web search with the error code an a couple of symptoms will find where someone had the same problem and have the fix for it.

[ScottS]

leave the gas cap off for a test drive, maybe your venting is not working and air can'tget into the tank fast enough .When you stopped and opened the tank , or when it sits overnight , air can get in slowly, when you drive it , it eventually runs out of fuel because the air can't get in.

Also a new fuel pump could be bad, it has happened before.

If you are getting a lean code that meas it can't get eough fuel . Or it is getting too much air , is there something that could cteate an intake leak when someting warms up ?

[littledh173]

I tried the gas cap trick, no effect. I thought about the fuel pump but I have never seen an electric fuel pump come and go as quickly as this does, not that it can't happen. Also when I had the fuel filter off I put a hose on the line from the tank and jumped the relay so the pump would stay on and monitored the fuel flow for 10 minutes with no change in flow or tone of the pump. I was thinking that maybe the pressure regulator might be failing but at this point I'm irritated enough that I'm guessing. To top it off I just made a couple of 15 minute trips with no issues at all. :-k

I didn't feel like paying for an answer either but I'm desperate.

Thanks for the replies as it does give me another point of view and that helps.

[crash]

seems like a bunch of us with 98 & 99's are having these similar problems. weird, i wonder if they are all programmed to self destruct at a certain date? LOL

[phr1$k37]

seems like a bunch of us with 98 & 99's are having these similar problems. weird, i wonder if they are all programmed to self destruct at a certain date? LOL

Yikes! As long as it stays away from '97s LOL.

Hey littledh did you get the codes interrupted yet? Sorry I am at work and would try to find a way to know what it means. A couple guys already asked if you were burning rich or not?

[HPbyStan]

My stock '98 AWD started screwing with me this wknd. I would be driving along and it would just quit running. First time I checked all the fuses and they were all good. Then I switched the fuel pump relay with the A/C one, as they are the same, and it fired right up. I went to NAPA and bought a new relay and put that in the fuel pump spot and returned the other to the A/C spot. A few hours later the same thing happens so this time I just removed the relay and reinstalled it and away we go. The connections all look good so I'm not sure what's going on here.

[phr1$k37]

Wow ... so the relay itself is not actually frying out (which would be a big deal if it did) ... but reinserting restores to working order. All wiring connections are good? So what is keeping the relay "open"? I thought this was all controlled by the PCM?

[LiftedAWDAstro]

My stock '98 AWD started screwing with me this wknd. I would be driving along and it would just quit running. First time I checked all the fuses and they were all good. Then I switched the fuel pump relay with the A/C one, as they are the same, and it fired right up. I went to NAPA and bought a new relay and put that in the fuel pump spot and returned the other to the A/C spot. A few hours later the same thing happens so this time I just removed the relay and reinstalled it and away we go. The connections all look good so I'm not sure what's going on here.

My 98 would do the same thing...just die all of a sudden. Sometimes it would re-fire while coasting and other times it would require stopping on the side of the road. I bought a fuel pressure gauge and drove with it attached and sure enough the pressure would drop to 0 psi and she would shut off. Replaced the pump and all is well.

[HPbyStan]

My stock '98 AWD started screwing with me this wknd. I would be driving along and it would just quit running. First time I checked all the fuses and they were all good. Then I switched the fuel pump relay with the A/C one, as they are the same, and it fired right up. I went to NAPA and bought a new relay and put that in the fuel pump spot and returned the other to the A/C spot. A few hours later the same thing happens so this time I just removed the relay and reinstalled it and away we go. The connections all look good so I'm not sure what's going on here.

My 98 would do the same thing...just die all of a sudden. Sometimes it would re-fire while coasting and other times it would require stopping on the side of the road. I bought a fuel pressure gauge and drove with it attached and sure enough the pressure would drop to 0 psi and she would shut off. Replaced the pump and all is well.

Well, That's how my story ends also. Fuel pump was a new Delco last Dec BUT the pump is what was bad again. We "short checked/ continuty checked" all the way to the pump instead of just checking the pump its self since we had just changed that in Dec but everything was good all the way to the pump its self. M A N !!!!!!!! Looks like all I was doing switching relays and checking fuses was just letting the pump rest and then it would go again for a short time.

[ihatemybike]

Wow, that's a short lived pump. Hope the next one treats you better.