I have an 87 350 TPI auto RMT with a new walbro pump and 24 lb injectors.
I am having a problem with my fuel pump loosing power and not building pressure and shutting down after around 45 min of driving.
At first its great but gradually looses power/ pressure, could a relay be causing this?
This just started last week, go out for a cruise and have to pull over for a few mins then starts up again.
While pulled over, turning on the ignition I noticed the pump or is completly dead or barly has power to turn over with little to no pressure.
Any ideas?

 

more than likely a bad pump. hard to replace tho. i dont think it is the relay. also check the fuel pressure regulator. if you checked the fuel pressure with a gauge at the fuel rails, it should be at 40 - 50 psi. and check your fuel filter too. could be clogged.

 

Fuel pump is new, filter is new, I have new adjustable fuel regulator and the pressure reading from the rail is anywhere from 30 - 40 psi.
The only thing not new on there is the relay but I have a feeling thats not it.
Everytime I start the car the fuel pressure seems to be slightly different without touching it.

 

even if the relay is bad the fuelpump should get its power throught the oilpressure switch while engine is on.

 

It could be a bad/damaged wire. walbro pulls more current than the factory pump and if either the ground wire or power wire were damaged it would heat up, increasing resistance etc. do a visual inspection of the feed wires and plugs for any heat damage/corrosion and check the resistance of the wires.

when you start the car back up after it quits, do you again get the full 45 minutes or does the time it operates continue to decline?

 

I changed the relay to one kicking around, still the same...
Only other thing I can think of is fuel pump or a loose wire, Im stumped.

 

When I first start it, the pressure can be between 29-40 psi, never stays the same.
While driving the first few mins its great but after that I can tell the pump isnt keeping up, have some flat spots under acceleration and after a good 45 or so it decides to die and has to sit for around 15 min restarts and gets me home.
When the car is off I turn the key to on, check fuel pressure which will read nothing or 20 psi and drop fast, after the 15 min it jumps back to 30-40.

 

tonight test it and rather than turning the key to just the on position and checking, have someone look at the gauge and try starting it. even if it doesn't start that should get you a true reading of the "running" fuel pressure.

 

Just curious, where are the wires that lead to the pump, I was under the car and hoses/ lines but not the wires.
Is it the 2 orange lines
I was considering even wiring the pump directly to the batt with a thicker gauge wire and use a switch.

 

you could run wirers direct from the battery and a simple switch, there is a contact in front of the rear axle just behind RH backseat you could connect to just to eliminate bad wiring, another thing to suspect is fuel pressure regulator....

 

You just answered your own question. It sounds like the pump is bad, regardless if it is new or not. As the pump heats up from usage, it is slowing down, and it needs to cool off to work at its full capacity again. Pull the pump and have it inspected, either that or just replace it with another one and be done with it....

 

You are probably right but Im trying to see if anyone else had a similar experience and diff solution, changing the pump is the last thing I want to do.
Im getting tired of working on that f#$@ing thing already, more dissapoinment than pleasure.

 

It is very common, unfortunately. I recently got my hands on an alky pump that was brand spanking new, but when we tested it it broke down as the need for it increased w/RPM. Sometimes you get a bad batch of parts, especially w/alternators, and fuel pumps are no exception, and they need to be sent back and exchanged. I'm friends w/someone that bought a fuel pump once, went through hell getting it into his TTA, only for it to die a few months later. He was so annoyed, and he DIDN'T want to drop the rearend to fix it, that he cut an access hole in the back. It happens, but the bottom line is that is more than likely the culprit. The only other thing that I can think of is maybe the fuel is boiling in the rails before it reaches the injectors because of the excessive heat, as that happened to me last week....

 

Strange, how was your fuel boiling?
Makes me wonder if my fuel would be boiling to make it loose power as well.
Funny thing is it runs amazing for 5 min then has some flat spots till it dies, this is just a stock setup nothing crazy with a turbo in low boost.

 

Gasoline has a boiling point between 100-400 degrees, and of course variables come into play. The fuel will boil, then change from a liquid to a gas in the rails prior to the injector, and this causes vapor lock. Very common on carbureted engines as well. The day it happened to me, I couldn't get my engine to run anywhere under 200 degrees because it was that hot out, even with both fans running constantly. It reached 220 just sitting in the pits, and you could literally hear the fuel boiling/bubbling in the rails when the engine was turned off....

 

What are you running to get those temps?
Did your friend find it easier getting to the pump from the top hole he made and how big was the hole.
Just thinking about the fuel lines that need to be dissconnected, did he had enough room to work?

 

My cooling system? Stock radiator, stock waterpump, 160-thermostat, and both fans set to trigger at 180 degrees. I don't run antifreeze in the warmer months, just straight water. My water temp only gets that high on very hot days, like today (90-degrees). The engine never see's more than 15-psi of boost....

Give me a minute to find the link, because he started a thread on one of the Buick boards. Hold on one second....

 

Here you go....

http://www.turbobuick.com/forums/tur...utes-less.html

 

Wow nice job, might consider doing that as well.
Thanks for the link

 

I made my access panel, turned out awesome.
Fuel access panels shouldve been factory, so easy to do and saves alot of headache.
Where can I connect a 12 or 10 gauge wire that runs with the ignition on only, to the pump without a switch?
Im not sure how much amps it needs if I went from the fuse panel.