[MinnSub]

Could some one help me out with the location of the fuel pressure regulator on a 1997 Sub, 5.7 liter. I Replaced the fuel pump (6th time in 4 years) This last time it still would not fire up and I suspect the regulator at this point as the pressure is good at the pressure relief valve. Do I actually have to do a tear down of this engine to get to the regulator? This is a bit crazy. Did they hide the little beast?

Thanks for any help!

Bryan

 

[MrShorty]

Start by saying that I'm pretty new to GM truck engines (bought the Suburban about 2 months ago), so I'm going on what my Haynes manual says and what I know generally of how fuel systems are designed.

Haynes says the FPR is part of the "fuel meter body" and is accessed by removing the upper intake manifold.

Why do you suspect the FPR is bad? From what I can tell, the fuel delivery system on these engines is similar in design to the fuel system on my Ford's: Fuel pump delivers fuel to the engine, FPR is a basic backpressure regulator bleeding off the excess fuel pressure back to the fuel tank as it maintains a constant pressure to the injectors. On a system like this, if the fuel pressure measured at the test port is correct (60 psi according to the manual), then the FPR is not a likely cause of the no start. Where you're measuring "good" pressure at the test port (I don't know how you've defined "good"), I'm not sure I would suspect the FPR as the faulty component.

 

[MinnSub]

Hello:

Thanks for giving some input here, it is all learning in some fashion.

The fuel systems on these truck is not reliable in any real way. The Ford system, at least the more recent ones have a step-up (2 pump system) which I have to believe is 800% better than the GM version. These trucks are well- known for the fuel pump issues. The original may last forever but once they start going it is a crap-shoot each day on if the truck will start. In 2005 I changed the pump 3 times, the last time it lasted 1 month to the day. A very poor design that has not been re-engineered, regardless of brand. This last pump is now another Delco, I have also had Carter's and Re-tech's.

That said.....the only other weak spot in this system that I know of is the FPR. In time it will be an issue. I have nearly 200,000 well maintained miles on the Suburban. With everything else as it should be the only thing I can come back to is that the FPR is bad. The pump is new, the pressure is well above 60, (good) and with the local parts stores affirming that they do sell FPR's often enought tells me that there is a possible cause of my problems.
I have a 1997 Sub (almost 200,000 miles) and a 1993 truck (207,000+ miles), 6 pumps into the 97 and 3 into the 93. I love the trucks they do what I need them to do .... when the fuel systems work. That is the only problem I have every had with either of these trucks.

I need to know if the FPR is under the plenum for sure. If in fact it is, once again GM complicated things when they didn't need to.

 

[84fiero123]

The duel pump system is inherently bad in the fords, I know its even worse in the duel tank system. My older ford van has it, and if the low pressure pump in the tank goes the high pressure pump will only draw down to half full. After that it won’t work.

I must agree the pumps in the GM trucks are badly designed, but all pumps in the tank go if you run them low all the time.

Sorry about you having so much trouble with your system but mine just ran over 192k and so far, nock on wood no problems with the fuel delivery system. Though I did have to replace the tank. I think if I have to replace the pump it shouldn’t be that big a problem. I’ve pulled it once without to much trouble. Although I don’t know about the system on the newer ones, mine is a 94.

 

[MinnSub]

The Ford systems over the past 10 years or so is highly reliable when compared to the the GM pumps. Our local Chev dealer can't keep enough pumps in stock at times. I am very familiar with the auto stores in our area and do a majority of my own maintenance and across the board in discussions of this topic the demand for Chev/GMC pumps is multiple times more than any other vehicle.

The original pumps will last, on our Sub the orginal went to almost 150,000 miles. Once it is replaced you never know when it will go again.
I do know a fella that has a 97 like ours and he is one up on us.... he is on his 7th pump. If someone could come up with a good/reliable replacement pump and/or retrofit system, they would make tons of $$ as the market is huge.

While running the truck with a low gas level is not good (on these trucks), it is not the deciding factor of the pumps going out. Shortly after our 1st one went, I was the main driver of our sub because my wife wanted a car and I very, very seldom let the gas level get below 1/2 (my wife kept it filled without it getting low as well) and that is something in the real world you just shouldn't have to worry about but with this issue you have to put eveything in your favor that you can. It made no difference in my case.
I put in 3 pumps from March 23, 2005 to Dec 24 2005, the lasted exactly 1 month to the day2! The one before that, almost 3 months.

 

[MrShorty]

My BII has a dual pump system, the Explorer has a single pump system. Neither of them has given me any trouble at 150K and 200K miles respectively.

I'll be interested to see what problem you find and how the FPR contributes to it.

Does anyone know if the PCM directly monitors fuel pressure on these?

As for knowing for sure if the FPR is under the plenum, I haven't been under there (yet), but I would trust the manual on this (and I will be the first to admit that manuals make mistakes). If you feel it's necessary, hopefully someone who's actually been in there can confirm.

 

[crjdad]

1997 K1500 GMC Sub

I had my fuel pump go out for the 3rd time. I am going to change it this time myself. I found out that checkers sells a bosch pump that they guarentee for life. Does anyone have any experience with this pump? Also, does anybody know a good siphening kit. It looks like I'll be doing this frequently. Thanks for any help/advice!!!

 

[jack77]

the FPR in this engine is under the upper intake manifold and contrary to popular belief it is very easy to remove and replace. this should take an hour at most. The biggest problem with any fuel injected engine's fuel system is lack of regular maintenance. The fuel filter should be changed at a maximum of every 12,000 miles. unlike carburated engines that run at 5 psi, these engines run at around 60 psi. when the filter is clogged the pump runs harder than it should and it kills it self. The regulator usually dies from dry rot in the diaphragm and then leaks gas straight into the intake. if it does that it should give drivability problems and eventually cause a no start from flooding.

 

[crjdad]

The regulator usually dies from dry rot in the diaphragm and then leaks gas straight into the intake. if it does that it should give drivability problems and eventually cause a no start from flooding.

Could this be the reason that my gas mileage is down to about 8.5 mpg? The sub is getting this mpg around town with the 4wd unit in 2wd and the front hubs have been confirmed unlocked.

 

[jack77]

Absolutely. it would be dumping staight gas into the engine.

 

[crjdad]

thanks a ton for your help. I'll be replacing the fpr right away.

 

[Dr_Zero]

Good info I guess I need to get off my duff and get the filter changed so I will have a definite time frame for future changes,