'89 BII Fuel Pressure Regulator question

[97fordrunner]

Hey guys well now that its cold I am having some more issues with the BII. This fall it was hard to start after it had sat over night or longer I usually had to cycle the key on and off about 5 times and then it would fire right up, now that it is averaging 0 at night in the am I have to cycle it about 10 times to get it to fire but it doens't start it does the one or two cyl. fire and dies. Then I have to cycle it another 10 times and it does the same and once more cycle 10 times and it will start up and run great. Truck has two fuel pumps, I don't think the frame mounted pump is stock. I was wondering if the fuel pressure regulator is supposed to be holding the pressure in the rail and its allowing fuel to bleed back.

 

[IMenriched]

Hey guys well now that its cold I am having some more issues with the BII. This fall it was hard to start after it had sat over night or longer I usually had to cycle the key on and off about 5 times and then it would fire right up, now that it is averaging 0 at night in the am I have to cycle it about 10 times to get it to fire but it doens't start it does the one or two cyl. fire and dies. Then I have to cycle it another 10 times and it does the same and once more cycle 10 times and it will start up and run great. Truck has two fuel pumps, I don't think the frame mounted pump is stock. I was wondering if the fuel pressure regulator is supposed to be holding the pressure in the rail and its allowing fuel to bleed back.

the regulator, FPR, is just that, it regulates the pressure. thinking that the frame rail pump is the one that has the check valve built into it for drain back.

that is not to say that the FPR is doing its job correctly either.

best to get fuel pressure readings to make sure. when was the last time you changed your fuel filter?

getting codes will help determine if other things are complicating the situation too.

 

[DisturbedMXer8]

I'm pretty sure that fuel pressure is maintained strictly by the fuel pump. It should have some kind of check that holds pressure when it's off. The pressure regulator regulates the fuel based on the vacuum that's being fed to it. The easiest way to check the pressure regulator is to get the vehicle running, disconnect the vacuum line from the back of the regulator, then check to see if fuel is coming out of it. The vacuum line should be just that: vacuum/air. If fuel comes out there, the diaphragm is ruptured and is allowing fuel to pass through, therefore not allowing the fuel pressure to be regulated correctly at all. I had it happen to my 88 Ranger. At first it just was hard to start and ran fine. As it got worse, it barely ran at all. It may not be the problem you have, but it's an easy one to check and at the very least eliminate from your possible issues.

 

[97fordrunner]

Took some readings tonight and psi is at 40 when idling so thats good, and no fuel coming out of the vacuum port of the FPR so its looking like the pump is the issue with eityher no or faulty check ball

 

[DisturbedMXer8]

Yeah, that wouldn't surprise me. Did you try watching the fuel pressure after you shut the vehicle off? If you immediately start losing pressure after power down, I couldn't think of anything else but a fuel pump issue. I know the trucks are weird with the way they calculate fuel pressure before the MAF, but the pump is the only thing I know of that actually holds the pressure at a given point.

 

[97fordrunner]

So here is a question for you guys, is it possible to swap in a fuel pump from a '90 BII that was a single pump system for the current low pressure pump that is in the tank. I guess I'd rather spend the $$$ on the in tank pump and have one pump than spend the $$$ on the frame pump and still have two potential problem areas. Thanks fellas

 

[DisturbedMXer8]

To be completely honest I really don't know for sure. I would think that you could do that, I was never really 100% sure why they every had dual pump systems on them in the first place. Any idea what it's purpose for the BII is, or rather why they need the second outer one? Find the answer to that and you find the answer to your question as well =P.

 

[IMenriched]

So here is a question for you guys, is it possible to swap in a fuel pump from a '90 BII that was a single pump system for the current low pressure pump that is in the tank. I guess I'd rather spend the $$$ on the in tank pump and have one pump than spend the $$$ on the frame pump and still have two potential problem areas. Thanks fellas

Yes it has been done....been scanning the tech library for more info....& it maybe there, just haven't found it yet.

I asked the same question to Allen some time ago and he gave me a list of things to do and watch for but it would be better for you to get it straight from him...PM him and I'm pretty sure he can fill in your q's