Fuel Delivery issue

family xj

Well-Known Member
Joined
Feb 19, 2006
Location
Jacksonville NC
Not sure where to start so here we go. 1990 Bronco with 302 and A/T in it. I bought it not running (for $800)and the guy said the fuel system had an issue. So I got it home and the wife started to diagnose the electrical portion. At the Fuel pump relay it was low on one of the readings (relay was new). So we went ahead and tried to check the pump. Pump didn't come on. But when we ran power straight to it, it came on. It did die shortly after though. So bought a new pump and put it in. Turn truck to run and nothing so we ran the hot wire again. Pump kicked on but nothing happened. So I blew air into the line at the filter (on the frame) going back to the tank to clear it out and it started working. Checked pressure on the Fuel rail and Nothing there. Bone dry. Blew air into the valve on the fuel rail and heard gas come back into the tank. Turned on the pump and still nothin on the fuel rail. Not sure where the clog is at or how to figure it out. Any ideas? What is the silver box on the fuel rail that has a vaccuum line going into the top of it. I am worried that the injectors will be clogged since the tank was so contaminated. Took a few hours to clean out the tank from all the garbage in it. If your in Jacksonville and want to lend a hand let me know. We could use it
 
I might have some free time next week man if you still need the help.
 
Most likely you have to replace the tank and pickup. There should be 2 pumps on that one. In tank low pressure and a high pressure on the frame rail right under the drivers floor board. Also check the plastic canister behind that pump for having a cartriage filter that needs to be removed per a TSB from Ford. You will have to buy the filter to get the O-ring to reseal because you will not be able to reuse it as it swells when you take it off.
 
We replaced the sending unit. Thats all fine now. It gets fuel to the Filter and through the filter. after the Filter there isn't another Pump. All I can figure is that for some reason it is clogged going to the fuel rail since no fuel comes out when you push down on the check valve. May just pull all the lines, fuel rails and blow them out
 
So today I pulled the filter and put air into the line going to the rail. Then had someone hold the schrader valve open. Some fuel came out but not alot. So I hooked the pump back up and still didn't get fuel to the shrader valve. Pulled it off the filter and blew air through it again. Then hooked up the pump and again nothing. So I am stumped. What if the two lines going to the fuel rail are backwards and the inline for fuel goes to the Regulator first? Would that stop the fuel flow and cause it to feel clogged? (is the regulator a one way flowing system) Next step is to pull the lines where they connect over the tranny, IF I can get to them
 
Found out today that the tank has a leak up high, well about the 6 gallon mark. Go figure. So I am going to drop it and fix the hole. I am going to run all new fuel lines. Before I do that I am goin to pull the fuel rail and clean it. Hopefully its not clogged and the line is. I couldn't get any fuel into the rail even after pulling the vaccuum and the schrader valve. Wish I had a arage to do this in so I coud see better at night.
 
Figured it out today. Pulled the return line and fuel came from the tan end. Turns out when I put the lines back on (just the way they came off) they were on backwards. So we have fuel all the way through the system. I probably don't have a leakk either, but rather had too much pressure on the line and it forced it to leak out. We shall see tomorrow. Battery was dead when I went to start it so we put it on the charer tonite
 
Got fuel to the rail and it will run on ether but can't seam to get fuel into the injectors from what I can tell. Going to check resistance on them next. Well at least the ones I can get to. Need to borrow an ODB1 reader and see what codes I am getting
 
So I plugged in a node tester to one of the injectors and it looks like I am not getting signal. So where do I go from there?

From what I can tell, no power into the Fuel pump relay and no signal to the injectors. Is this a PCM issue?
 
It could have a bad EEC Power Relay. It should be mounted near the fuel pump relay. If it is bad the computer wont power up, it also sends power to the fuel pump relay.
 
I pulled my ECM and found this. I believe this is my problem

ai93.photobucket.com_albums_l64_Maysville1990_ECM.jpg

ai93.photobucket.com_albums_l64_Maysville1990_ECM1.jpg

ai93.photobucket.com_albums_l64_Maysville1990_ECM2.jpg

ai93.photobucket.com_albums_l64_Maysville1990_ECM3.jpg
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Electrolytic capacitors are famous for leaking and burning up boards, bring it to somebody who knows circuit boards and they can desolder and inspect the tracings to see if its fixable. As long as the tracings aren't burnt up you should be able to replace the caps for cheap.
 
ok I got the new EEC and put it in and still nothing. So I am not sure where to go from here. No power to Fuel pump relay, no power at EEC relay, no power at injectors when turnin over. Ignition is fine as I pulled it from a running Bronco at a scrap yard.

Ideas?
 
Stumper... without power ON the EEC relay, you'll get nothing anywhere else. Since the EEC relay is feed directly from the battery (assume via the solenoid?)... maybe you've got a wiring issue between the 2?

awww.veryuseful.com_mustang_tech_engine_images_88_91_5.0_EEC_Wiring_Diagram.gif
 
Broke down and got an old timer mechanic over here today to help. He spent 8 hours testing and finally got it running. There is an issue with my relays (fuel pump and EEC). He made them bypass (close) and it started right up. We also found out that the oil pump shaft going from the distributor to the oil pump was missing. We replaced it and found that when we started the truck the oil pump would spin the distributor knocking it out of time. So now we will raise the motor drop the oil pan and change the pump. Going to look at the bearing and possibly replace them if they are bad. I think they have some wear on them due to the milage.
 
Can anyone explain why he can make a jumper on the Fuel pump relay and the EEC relay and the truck will start?

When he does the jumper on the fuel pump it kicks on the pump then he does the jumper on the EEC and it starts. Ideas?

Let the truck run for 20 minutes the other day and it sounds great. Set the timing and and found an oil leak and manifold leak. I just need to make it run without using a jumper wire.
 
I keep looking at the chart and think I understand and pretty sure I know how to test every thing. Only thing I am not sure on is the ground. Will the round be a constant ground or only when the Key is on?
 
Ok here is what I am doing
Key on Fuel pump relay test small wires
ai93.photobucket.com_albums_l64_Maysville1990_Fuelpumptestsmallwires.jpg


Key on Fuel pump relay test small wires results
ai93.photobucket.com_albums_l64_Maysville1990_Fuelpumptestsmallwiresvoltage.jpg


EEC relay test Large wires
ai93.photobucket.com_albums_l64_Maysville1990_EECLarewirecontacnttest.jpg


EEC Relay test large wires results
ai93.photobucket.com_albums_l64_Maysville1990_EECLargewirecontsanttestVoltage.jpg


EEC small wires
ai93.photobucket.com_albums_l64_Maysville1990_EECRElAYHarnessTestSmallwires.jpg


EEC Small wires Key off results
ai93.photobucket.com_albums_l64_Maysville1990_EECRElAYHarnessTestSmallwiresKeyoff.jpg


EEC Small wires Key on results
ai93.photobucket.com_albums_l64_Maysville1990_EECRElAYHarnessTestSmallwiresKeyon.jpg


My question is on the large wires for the EEC when power is off should the one not from the battery act as a ground?
 
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