Fuel Pressure Issues

[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

 

[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.

 

[jkufen]

But I knew in the beginning it had low fuel pressure. That was the first thing I noticed when I pressed the bleeder valve on the engine. No I never knew the exact psi but I knew it was low. I also knew the pumps were good or at least running because I jumped them directly from the battery and they came on. My issue was I wasn't able to determine what else the issues could be until I read that post I posted about the engine computer going bad. When I mentioned it to the guy at the shop and when he checked it he determined it wasn't working properly. Besides the computer which was the next thing I would have had to replace would have helped but the mechanic had to use some kind of scope (don't remember what the first part was) to determine the issues with the distributor. I had the ignition module tested at the local parts store and it came back as good but it ended up being bad. The issues with the bronco were not things I could with my know how diagnose myself. I could have went through every component in that truck but I would have never determined the issue. So with that being said it would have done me no good to test the fuel pressure because it made no difference in the outcome. Another curve ball was when the mechanic ordered the 1st computer the engine didn't run any better. Come to find out the new computer was bad also so that would have really messed me up because I would not have thought the new computer to be bad. The issues with my bronco were just out of my know how so I had to let the mechanic figure it out. Hopefully it'll be the last time.