Hopefully a bad fuel pressure regulator

[Myotis1134]

Over the past couple weeks the lumi has stalled a couple times when I'm coasting, then refused to start for a bit. Also more frequently when I seem to park on an incline or decline (even a slight one), sometimes it will fire right up, but if it doesn't start right away then I have to let it set for about 10 minutes before it will run.

 

I was leaning towards the fuel pump due to a recent misadventure where I turned it over every 30 seconds to a minute, for about 10 minutes, then got under the hood to look around and didn't smell any gas. However, I replaced the fuel pump less than 4 years ago with a brand new one. However, when I turn the key and prime the pump, I also hear what sounds like bubbles in the tank.

 

Tonight after getting off work, I pulled the car out of the shop and left it idling outside for about 4 minutes after which it died. No spluttering, just died. Luckily a couple bays down, a guy I've gone mud-bogging with was working on his beast late, so I borrowed a fuel pressure gauge and plugged it onto my rail. Initially I got just over 40 psi, but over about 10 seconds it would go down to nothing. Hopefully this means that my pressure regulator is gone, and the bubbles I heard were the return lines blowing air back into the tank. I haven't had time to pull the vacuum line yet, but I'm about to do that.

 

It's 6 below here in AK at the moment, and I REALLY don't want to have to drop the tank on the donor to get at the pump. Are there problems with my logic here? (not about working in the cold, but the problem).

[jman093]

I'm leaning more towards a weak fuel pump. When fuel pressure drops low, pull off the return line from the rail and see if fuel starts rushing out. If it doesn't you have a weak pump.

[Myotis1134]

Went ahead with the pressure regulator swap because it sounded like the "easiest" part. Thanks for the heads up guys - this has seriously turned out to be a pain in the ass. At least now I know that there is no such thing as a 'simple' fuel pressure regulator swap on a 91 lumina. Going to have to pull the whole fuel rail, and getting the injectors right was a nightmare when I installed them. At least I got the garage.

 

I'm betting you're right jman. Is it possible that it could be electrical? I was browsing some posts and found a wiring upgrade from ZZPerformance?- heavier gauge wire and the like. Figure if I'm going to drop the tank, might as well put in some better wiring. I'm kinda iffy about grabbing a pump from my donor or the Z34. I know the donor ran, but it sat a year before I got my hands on it, and I don't know when the Z34 ran last. If I get a new pump, any suggestions as to brand? Does it matter?

[AL]

Walbro is what most people have the best luck with

[Crazy K]

BOSCH FUEL PUMP from ADVANCE AUTOPARTS, with a lifetime warranty if you buy all the related filters!!!!

Bosch pumps are very good, but not to be confused with their spark plugs or oxygen sensors which suck in our cars. the 96 GP has 210,000 miles on a the same bosch pump and has a thirsty L67... and I have used the same pump in other vehicles, as well as other members happy with their pump performance..

 

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Edited November 19, 2011 by Crazy K

[Myotis1134]

Got the FPR out of the donor last night. Cleaned it up, installed it and put everything back together. Was actually kind of good I did this; was able to fix one of the coolant hoses to the TB that was slightly leaking, because I cut it too short. Anyways, fired it up, ran like a charm. Pulled it outside to see what would happen, and it died about 5 minutes later. Annoying.

 

So the pump and wiring is the next thing I suppose. Thanks to Al and Crazy for the brandvertising, I'll probably end up going with the cheapest of the two.

[Crazy K]

P.S. If you find a Walbro from a reputable source you will be paying alot more that the BOSCH. While a Walbro is an excellent pump, cheap ones from e-bay and other sources are often counterfeit. The Bosch is also excellent, and comes with a lifetime warranty, so you can't go wrong.

 

if someone does have a link to a legitimate source for Walbros at a good price, do share.

[White93z34]

I have Bosh pumps in 3 of my 4 cars now. Some for several years. Always done me good. Only reason its not 4/4 cars is because I have not had a reason to replace the last one yet.

[Myotis1134]

I think I'll go with the Bosh. Gotta love those lifetime warranties. Just in case part of the problem is electrical, can anyone shed some light on these wiring upgrades I'm seeing? I've come across 2 so far - one from ZZP http://shop.zzperformance.com/store/p/72-Fuel-Pump-Rewire-Kit.aspx, and one from HFP - it's their 'hotwire kit' http://www.highflowfuel.com/c-173564-performance-fuel-pumps-hfp-hotwire-kits.html. Yeah just checked, the w body store sells a hotwire kit too. What's the deal with these? worth looking into?