fuel delivery problems, any ideas?

[jay421]

i have an 86 bronco II. i was driving and all the suddden it started getting starved for fuel and misfiring then it died. it still cranks over but won't start, and u can not hear the fuel pumps turn on. but i had replaced the in-tank fuel pump and fuel assembly about six months earlier, also i checked the high pressure pump on the frame rail-took it off and applied power and it works. Seems as though no power is making its way back to the pumps. Could this be a relay or something? fuses inside the car are good. it has to be something electrical i just dont know what? if anyone has any ideas please help! thanks..

Jay

[didittwice]

Yes if there is no power when you turn the key on it is the relay
I have a 86 also mine would stop working and then go get it later and it would run for a while it drove me crazy but it was the relay under the hood the fuel pump is the one with the green plug now if you part store is like mine you will not get the right one what you need to do is change the plug that will go with the new plug I went to autozone.com and punch my info in and go to fuel pump and the you can find the plug it has been a little whill so right off the top of my head I do not remember but I can get the info if you need me to.
after that I have no problem with my fuel pump.

[drofman]

check the wires at the inertia switch

[oneway]

Yes if there is no power when you turn the key on it is the relay
I have a 86 also mine would stop working and then go get it later and it would run for a while it drove me crazy but it was the relay under the hood the fuel pump is the one with the green plug now if you part store is like mine you will not get the right one what you need to do is change the plug that will go with the new plug I went to autozone.com and punch my info in and go to fuel pump and the you can find the plug it has been a little whill so right off the top of my head I do not remember but I can get the info if you need me to.
after that I have no problem with my fuel pump.

that's a long sentence.

[didittwice]

Did not want to spend the money on the repair manual so I dont no where all the keys are so I have to hunt and peck and I did save space so there can be more post but did find some................................is the enough you can put them where you like this is how I hunt and peck

[jay421]

was it the fuel cut off relay? or the fuel cut off sensor? if u got to parts train.com they have both-don't know which

[didittwice]

According to my book and when I order parts it is just the fuel pump relay the problem I had was the configuration of the prongs.
The plug right next to the fuel pump is the eec relay if you look at the wriing diagram the are the same the prongs are just different.
So it will not plug in and I was not abel to get the one that would plug in so I had to change the plug.
I would get you more info but I work night and i am going to have go to work I will look it all up tomorrow.

And sorry about the one long sentence some day I only run 3-4 hours of sleep.

Craig

[didittwice]

HI Jay
I look and part train.com and the two you said are not the ones I put fuel pump relay and it came up with a universal I am not sure about this one.
I went to auto zone .com and they show what I used.
The harness is part number 538 and the relay is part number 1991.
This is the way I had to go they stop making the ons that is in the 86 it took a couple of trys before I figure it out.
auto zone might ship it to you one is 13$and the other is 11$ then shipping.
OK if you need any more help just let me know I am on days of now.
Craig

[drofman]

you can jump the relay to see if it's a relay problem.

[drofman]

if you jump the relay and still have no power, check inertia switch

[oneway]

Did not want to spend the money on the repair manual so I dont no where all the keys are so I have to hunt and peck and I did save space so there can be more post but did find some................................is the enough you can put them where you like this is how I hunt and peck

awesome

[zookeyknee]

BEEn there done it got the T shirt when it comes to your problem.My 87ll 2.9 5spd 4wd did the same thing conk out fuel starved. After 10 30 minutes of sitting it would start and run just fine. To narrow down the problem i carried a can of starting fluid with me when it happened again I loosened the ring on the air supply tube at the intake plenum slid it off and gave it a good spray if you have someone with you have them floor gas pedal to open flap there or hold it open w screwdriver. if it fires and trys to run its a fuel problem. I checked the relays and they were pretty corroded at terminal connector blocks removed the relays & with emory cloth sand paper and scraping with a small screw drver cleaned them up Ran fine again for three weeks then clonked out again .was fuel prob again thanks to starting fluid test.Then I got new relays at advance auto The EEC relay and fuel pumps relay are basically the same except one may have 4 prongs others 5 They will both work as the extra prong slides into an empty slot. the a/c relay also interchanges . On your 86 Bll the fuel pump and eec relays are above the pass side fender under the hood may have a plastic cover over them. the fuel pump and eec relays were origionally bolted to the metal inside of the fender using a short metal strap .through neglect they may just be laying there falling where they may since they dont have to be grounded by the strap that shouldnt be an issue.To find your fuel pumps relat the wires running to it for an 86 arered tan/lt grn yellow and org/lt blue. To jump test you want to jump wire between the yellow and org/lt blu. make sure inertia sw is set. You should hear pumps kick in when jumped with key off.To test relay function run a hot wire from + batt termto to the tan/lt grnand a ground wire to red the pumps will come on and problem lies in electrical.I Replaced all My relays some twice same story runs great clonks then after1to2 hrs or overnight it would miraculissly fix itself and run like a top before i could have a mechanic look at it it was always running .It died on me a month ago and when it would not start for a day I had it towed to my mechanic so i could at last solve my problem.Wouldnt you know it when my mechanic tried it it fired and ran like a new truck. He checked my wiring at the two pumps cleaned them replaced both fuel filters.So the only thing left is the in tank filter we think that something is floating around (loose screen) or floating gunk that may be causing all these breakdowns and then fixing itself every time .I ordered new sending unit w fuel pump sincce my gas guage only worked for half a tank then E .since you replaced your pump first follow those wire colors and test it .Good luck my problem started out as did yours and after a year wrestling this problem this has got to be it.ill let ya all know.Beyond wts end

[tonymasone]

Seems like I'm having a few of the same problems! My 87B2 is doing the exact same thing, drove it to work yesterday morning, (here in Pittsburgh, PA it was about 18 degrees last night), went to leave work at 5pm won't start, no fuel. You can easily hear the fuel pumps fire up and I wasn't getting anything. Got a ride to work this morning, went over to the B2 started right up...... I'm gonna start with trying to replace the fuel relay... hopefully that fixes it. Also I was wondering what would be involved with swapping in an 89' in tank fuel pump wiring wise. I have an 89' junker that's sitting in my back yard that I know the fuel pump is good on.

This time of year is definitely the worst time to have a lack of confidence in a vehicle being able to start. :(

[RakerBill60]

Mine did the same thing, and I replaced the fuel inertia switch under the dash in the middle on top of the trans hump. No problems since. I would start it up, go to work, go to start it, and nothing. I would reach down, push the reset switch, and drive it home. Did it a second time, I replaced it.