bronco II cuts out alot

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forman621
Posts: 49
Joined: Mon Jul 06, 2009 1:22 am

bronco II cuts out alot

Post by forman621 »

My bronco II has been running bad for a long time. it is an 86 bronco ii and at first it was running rough all the time. so i checked fuel preassure and it was under spec. running about 31 psi at idle when it should be between 35 and 45 psi. so i replaced filter still didnt do anything so i replaced the high preassure fuel pump on the frame rail. it runs better but havent checked fuel preassure again yet. but now the problem is that when the truick is under load and at operating temp it cuts out. but is only momentary. it is really bad when going up a steep hill. i have no idea what it could be. when it dies i have to let it sit for a couple minutes before it starts and runs enough to put it in gear. when i get up to speed it will run decent but still cuts out just not as much.

the rpms go down just a little
happens under load or on trail hills
hard restart
when i step on gas to try to keep it running, rpms drop and cuts out. feels like it doesnt realize that i am giving it air and cant figure out that it needs fuel.

what could i check next?
milwaukeeace
Posts: 5
Joined: Sun Apr 04, 2010 3:31 pm
Location: Milwaukee, WI

Re: bronco II cuts out alot

Post by milwaukeeace »

I'd try replacing the fuel pressure regulator. NAPA carries them for less than $30 and it's an easy fix. I replaced mine and it cured a hesitation issue I had.
forman621
Posts: 49
Joined: Mon Jul 06, 2009 1:22 am

Re: bronco II cuts out alot

Post by forman621 »

well the preassure regulator is fine there is no fuel going into the vacuum control and thats the way to check it it is fine.
i was also wondering if any one think that it could be the small filter in tank connected to the fuel pump?
drofman
Posts: 487
Joined: Sun Dec 27, 2009 9:36 am
Location: san dirgo

Re: bronco II cuts out alot

Post by drofman »

I had a problem with the lift pump in the tank.There is a piece of rubber hose between the pump and tube that swells. It would even die then restart when it had a full tank.
KRE
Posts: 30
Joined: Sat Nov 15, 2008 5:09 am

Re: bronco II cuts out alot

Post by KRE »

Any time you believe your having fuel pressure issues, hook up your gauge with a long hose and drive the thing down the road. You can place the hood on the safety latch and run the hose w/o pinching it. If the pressure is anything above 30lb and it's still having the issue it's not a fuel pressure problem. Most fuel pressure problems(other than filters) turn out to be TFI problems in the long run.
forman621
Posts: 49
Joined: Mon Jul 06, 2009 1:22 am

Re: bronco II cuts out alot

Post by forman621 »

alright cool i check those things again and get back to you guys. i was just wondering how many people have replaced their TFI module because of the same symptoms?
forman621
Posts: 49
Joined: Mon Jul 06, 2009 1:22 am

Re: bronco II cuts out alot

Post by forman621 »

ok now the bronco has two new fuel pumps and it still hesitates. the fuel preassure goes down to 10 psi so now i need to check while the pump is running low preassure voltage at the pump and see if recieving proper power. if it does drop power only at operating temp does anybody think that it could be the tfi module?
thanks you guys
KRE
Posts: 30
Joined: Sat Nov 15, 2008 5:09 am

Re: bronco II cuts out alot

Post by KRE »

You have replaced the filter on the L/S frame rail, correct? Also check to make sure none of the fuel lines are damaged in any way to reduce flow.
forman621
Posts: 49
Joined: Mon Jul 06, 2009 1:22 am

Re: bronco II cuts out alot

Post by forman621 »

Ok i replaced both filters and that includes the cartride filter. which i thought was the problem. Then i tried to start the truck and it only had 10 psi and wouldnt start. we pulled one of the fuel lines off and there was no fuel. :wtf: So i unplugged the high pressure oump and hot wired the low preassure pump to see if any fuel was coming out of the tank. which i found out that there was no fuel coming out. I hear the pump in the tank running. i just put that pump in and we tested it before we put the tank back in and it spit fuel. I have no i dea why it isnt any more.
I need some help and ideas.
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