Fuel Pressure Issues

[jkufen]

Well I have been having issues with my B2 for the past 2 months. I changed the relay, dropped the tank and changed the strainer on fuel pump. Also I had to wire in a new fuel pump relay connector. I have both pumps coming on and they truck is still running poorly. Every time I hit the gas it sputters and chokes. I don't have a way to test the pressure and get a psi reading but when I push the the little bleeder valve on the top of the end there is little fuel coming out. It comes out but only shoots out about 2-3 inches high. When I push the bleeder valve on my dad's ranger engine it shoots out 7-8 inches and has a lot of pressure behind it but my B2 doesnt. I changed the fuel pump regulator and it still has poor pressure. Any ideas what could cause poor pressure? Both pumps come on and I took the fuel lines of and blew they out with my air compressor. I am at a lose I guess if by next Saturday I don't have a solution I will have to take it to a real mechanic. I guess I am going to have to change out the fuel pump under the driver door and see if anything changes. Hope you guys have a solution for me.

 

[trail B2]

Have you thought about going to Harbor and getting a cheap fuel pressure gauge? I borrowed a cheap one last year worked great.You didn't mention changing the filter in the unit under the drivers seat that could be it but not very likely.Don't rule out electric problems I've had weird issues with those.I feel for you fought a lot of these problems myself.

 

[jkufen]

well i checked the filter under the door and it was rather dirty so to prevent anything at all clogging up the flow i removed the filter all together and put the canister back up. I am going to put a new filter in just not until I figure out what is killing my pressure.

 

[PetesPonies]

You have done too much work to not have checked the fuel pressure correctly and see if it is even an issue. Go about it right.

 

[chazzone]

You have done too much work to not have checked the fuel pressure correctly and see if it is even an issue. Go about it right.

^^^^What he said. A pressure guage is cheap, and should have been the 1st thing you checked.

 

[jkufen]

But i know it has bad pressure so what good is knowing the exact psi going to do me? Will knowing the psi tell me what is the issue?

 

[PetesPonies]

If you know that, then why do you need us? Seriously, you cannot be sure by what you have told us.

 

[jkufen]

My question was what can cause poor pressure. I knew i had low pressure but i was here asking what else besides what i have already done can cause poor pressure.

 

[jkufen]

Well after almost 3 months of fighting the bronco I finally took it to the mechanic. After about 4 hours of working on the bronco the mechanic said that the engine computer is bad. It is amazing to see how fast you can figure out a problem when you know what the heck you are doing. Also in that 4 hours he wired in my Fuel pump relay plug. Then he only charged me $48 for labor. He is ordering me a reman computer from philadelphia for $148 so hopefully by the weekend ill be riding again. I have been itching for a mud hole for the last few months and we have just gotten a lot of rain so this weekend will be perfect! Just hope the computer is my only issue!

 

[PetesPonies]

Well whereas the computer will turn on the fuel pump relay, it doesn't control the pressure the pump can generate. So again . . I go back to this:

You have done too much work to not have checked the fuel pressure correctly and see if it is even an issue.

which it seems now it is not.

 

[jkufen]

Well I am leaving that up to the mechanic. I don't know what exactly they did to the truck. They might have checked the pressure not sure. He says that when he bypasses the computer the truck will run a little better but it still runs rough because the computer is not in the loop. The computer will be in Thursday so hopefully by the end of day Thursday or Friday morning I will know whether or not the computer was the issue.

 

[PetesPonies]

It won't run at all without the computer, not a bit. So either your misunderstood him, or he is feeding you a line.

 

[jkufen]

Well I guess we will see Friday if that is the issue or not.

 

[Aleksfoxtrot]

It won't run at all without the computer, not a bit. So either your misunderstood him, or he is feeding you a line.

Yup the computer controls the injectors. No injectors no fuel. Also the spark advance I believe is computer controlled.

 

[jkufen]

I believe the mechanic said that the computer is just not energizing the pumps. I don't think the entire computer has quit I just think something on the inside quit. I know nothing about the inter workings of the computer but I am sure that one part of the computer can quit while some other parts work.

 

[Aleksfoxtrot]

Well I just had a fuel delivery problem with mine. The computer sends a ground signal from test pin 22 on the eec 4's that closes off that fuel pump relay and sends power to the pumps. My computer was sending a positive signal on all pins it was supposed to be closing grounds. I thought it was computer but after more diagnosis and head scratching I happened to find the ground plug up by the battery had come loose. I felt like an idiot. Plugged it in and it worked great.

 

[PetesPonies]

Well see that makes a big difference and why the words have to be carefully conveyed. Remember this?

Well whereas the computer will turn on the fuel pump relay, it doesn't control the pressure the pump can generate.

So of course it powers the pump, as said above. It turns on the relay, the relay energizes the pump. You could turn the pump on by bypassing the OEM circuit and perhaps that is what your mechanic is doing. That is plausible. But also as Alek explained above . . doesn't always have to be the computer's fault.

 

[jkufen]

Well the Bronco is running good again. The mechanic put a new computer in it and he said it still wasn't running 100% then he replaced what I believe was the rotor button in the distributor and it is running great! I haven't drove it yet but my dad called me and said it was running better than ever. I am driving down Monday to get it from my dad's house and probably go and tear it up again before Monday is over with :icon_rofl:

 

[jkufen]

1 engine computer = $137.70
1 ignition module = $59.01
1 distributor stator assembly = $27.09

Plus labor = $192.00
Plus tax

Total = $428.43

It ended up costing me more than I wanted but if I would have taken the low fuel pressure and bought new pumps like my buddy wanted I would have been a lot farther in the hole! Glad to have the bronco back in action!

 

[PetesPonies]

Do you NOW see why I was so adamant about checking things carefully before making "decisions" about what is wrong? I kept asking what the fuel pressure was. And, that ended up not being the problem. You would have known that in the beginning if the pressure was checked. This is a learning point. cars/trucks/engines can be fun and frustrating ,both. So when trying to fix a problem, you have to go about it step by logical step.