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i Have an 89 f-150 with a 5.0 slightly modded but nothing major. it ran fine for 2 months after the rebuild but now it stalls at half throttle. i can get it to rev up to 5000 rpm and it sounds and runs great but once my gas pedal goes past halfway it stalls. no spit or sputter, it instantly dies. fuel filter has been changed as has the regulator. exhaust has no blockage, no air blockage help please im baffled

Submitted: 25 days and 1 hours ago.
Category: Ford
Value: $15
Status: AWAITING CUSTOMER ACTION
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Optional Information

Year : 1989
Make : Ford
Model: F-150
Engine: 302

Already Tried:
fuel filter, fuel regulator, valve adjustment, intake manifold gasket, clean iac and throttle body.

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

Has the throttle position sensor been replaced?

25 days and 1 hours ago.

Reply

Yes replaced the tps

 

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

Try disconnecting the egr vacuum line and running it. See what happens.

25 days and 1 hours ago.

Reply

egr is blocked off and has been since rebuild

 

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

What is the fuel pressure when this happens?

25 days and 1 hours ago.

Reply

34 psi at idle 42 when it dies

 

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

Will it stall in park at half throttle, or will it stall in gear at half throttle while holding the brake?

25 days and 1 hours ago.

Reply

in park or nuetral it stalls at half throttle in gear it stalls at half if it dosent stall going into gear sometime just puttin it in gear and it stalls

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

Do you ave a timing light to hook up to a plug wire to see if it is loosing fire when it happens?

25 days and 1 hours ago.

Reply

it is at 10 btdc with out the jumper 22 btdc with jumper spark does not cut out

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

Do you have a noid light to put in the injector harness connector?

25 days and 1 hours ago.

Reply

no sir i do not

 

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

They are really cheap at the auto parts stores ($10 in my area). Get one and let me know when you have it. We will continue after that.

25 days and 1 hours ago.

Reply

no prob

Posted by Dieseljunky2 25 days and 1 hours ago.

Info Request

ok

25 days ago.

Reply

got a set of noid lights what do i do now

 

Posted by Dieseljunky2 25 days ago.

Info Request

Disconnect any easy to get to injector electrical connector. plug the noid light in to the connector. Start the engine, you should have a steady flash in the noid light (it may be fast enough to look like it is on constantly, just dim). Rev the engine like you do when it stalls. watching the light see what it does, get brighter, turn off when the motor stalls, nothing?

25 days ago.

Reply

it blinks and increases as rpm increases and when the engine stalls it follows the rpm of the engine dosent cut out or pause

 

Posted by Dieseljunky2 25 days ago.

Info Request

Disconnect the throttle position sensor, hook the injector back up. try the stalling again.

25 days ago.

Reply

no change at all

Posted by Dieseljunky2 25 days ago.

Info Request

Hook the throttle sensor back up. have you tried running it with the air intake hoses disconnected from the throttle body?

25 days ago.

Reply

yea the air hoses have no effect first thing i tried

 

Posted by Dieseljunky2 25 days ago.

Info Request

I am about out of brain power here. try unplugging the map sensor connector (black plastic box with a vacuum line going to it), usually around the a/c box or battery.

25 days ago.

Reply

no change my neighbors a mechanic i am a diesel mechanic and neither of us have had any luck figuring this thing out for the past two weeks

 

Posted by Dieseljunky2 25 days ago.

Info Request

Reconnect everything, and unplug the alternator, I have heard of RFI interferance from alternators, but have never had it happen to me before.

25 days ago.

Reply

no go it back fired a little though

 

Posted by Dieseljunky2 24 days and 23 hours ago.

Info Request

The last thing I want to try before I let another expert have a crack at this is for you to look under the dash and make sure there is no wiring harness hitting the top of the accelorator pedal arm and shorting out when it moves.

24 days and 23 hours ago.

Reply

nope god i wish it were that easy but im packin up for tonight ill try again tomorrow

Posted by Dieseljunky2 24 days and 23 hours ago.

Info Request

I am goig to throw this question out for the other experts to ponder upon. Good luck

24 days and 23 hours ago.

Reply

thanks i need some luck right about now

Posted by Dieseljunky2 24 days and 23 hours ago.

Info Request

No problem

24 days and 3 hours ago.

Reply

any new i deas an the 89 ford

Posted by Dieseljunky2 24 days and 2 hours ago.

Info Request

No one else had any ideas either, they all agreed, that we covered everything. Everything except the processor, which I have no way of testing with out hooking up to the truck. I would suggest a processor next, but I am only saying that it will be a shot in the dark as to whether it is the problem.

23 days and 23 hours ago.

Reply

well its better than nothin, ill see if i can find a cheap junker to throw in, if it fixes the problem ill invest in a reman or new

Posted by Dieseljunky2 23 days and 18 hours ago.

Info Request

Let me know what happens.

14 days ago.

Reply

well the computer did not help but when i pull the spout connector to time the engine the timing dosent really move. without the connector the timing is at 10 btdc, with connector in the timing is at 12 btdc. i was under the impressin the timming should change by 17 to 23 degrees

Posted by Dieseljunky2 14 days ago.

Info Request

I have always seen it jump up around 25 degrees. OK, try this for fun, take a pair of jumper cables and hook the negative to the negative battery post. Hook the other negative on the intake manifold. take one positive and hook to the alternator housing (not the positive post) and hook the other positve to the body of the truck. The purpose of this is to make sure everything has a good ground. See if it changes the running any.

14 days ago.

Reply

i will do tomorrow

Posted by Dieseljunky2 14 days ago.

Info Request

OK

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