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Discussion Starter #1
Just signed up for the Site and this Bronco is New to me.

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. 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 and it started working. Checked pressure on the Fuel rail and Nothing there. Bone dry. Blew air into the valve 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 ine 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
 

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That silver box I think you're referring to is your fuel pressure regulator that has a vacuum line running in to it. I would check the fuel pump relay.
Above and behind the brake booster 87-91 has the fuel pump relay and EEC relay above the wheel well behind the air filter housing.
 

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Discussion Starter #4
10-18-2011

Thanks for the picture.

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.
 

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Have you checked to see if you have two fuel pumps? Iam not sure about 90 model but, our 86 and 88 have a pump in the tank and one inside frame rail before the filter.
 

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Maybe some more pictures of the Fuel Delivery System will help, remember these are from a '94 Emissions Manual, and you have a '90. I don't know if there were significant changes made between those two model years.

Click on the links below the pictures to see them full size

Fuel Pump stuff:

http://www.supermotors.net/registry/media/892442_1

http://www.supermotors.net/registry/media/892443_1

http://www.supermotors.net/registry/media/892444_1

And the fuel regulator:

http://www.supermotors.net/registry/media/892441_1

Good Luck
 

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Discussion Starter #8
Found today that the tank has a leak up high. o 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
 

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Discussion Starter #9
Got the fuel issue figured out on the truck tonite. They had the fuel pump lines backwards (so when I took them off and put them back on they were still wrong). Go figure. I don't think the tank is leaking but we will see tomorrow. Battery is dead now so its Charging tonite
 

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Were the two lines (supply and return) the same size?
 

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Discussion Starter #11
Yes they were from what I can tell. So today I went to start it and it won't start but will start if I use ether. So now I am going to test the injectors and see what the resistance is for them
 

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Discussion Starter #12
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?
 

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You definetley have the leakage on those caps. Wonder if there is info somewhere on replacing them or do you have to get a new ECU?
 

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Discussion Starter #15
The guy I compared mine to said he replaced his. Definitely not something I can do. A new EEC from Oreilly was only $100.
 

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Discussion Starter #16
ok I got the EEC put in but still nothing has changed. I have no idea where to go from here. No power to fuel pump relay, no power at injectors, tried testing codes by using jumper wire but the Check engine light just stays on. Definitely starting to get frustrated with this thing. What steps should I take.
 

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Do you have power to the eec relay? IS the EEC relay working? The EEC relay supplies power to one side of the fuel pump relay.

BTW... the FP relay should have two sources of power. One to the trigger side ( one of the little pins) which gets power when the EEC relay is closed (sending power)
AND power from either a fuse, or a fuseable link (depending upon the year) that makes one of the larger pins hot all the time.
 

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Oh... I just checked, you have a '90 bronco.

The PCM does not supply power to the injectors or fuel pump. It controls both by supplying grounds.

The EEC relay supplies power to the injectors, and as mentioned above to the fuel pump relay. The other side of the fuel pump relay gets power from a fuseable link. I *think* the fuesable link gets its power from the battery side of the fender mounted starter relay.
 

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Discussion Starter #19
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 bearings and possibly replace them if they are bad. I think they will have some wear on them due to the milage.
 

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Discussion Starter #20
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.
 
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