OK...long story...so here are details only. 1989 4 banger.

Symptoms: truck stalls when you give it throttle. Idle sounds good and strong, but as soon as you gas it, the engine cuts out.

Dealer Diagnosis: oil in distributor...cost $1000. They are smokin somethin. Checked distributor, everything checks out.

2nd Opinion from trusted shop: No clue here. Thought it might be out of gas as it stalled when going up hill, perhaps faulty fuel gauge. No dice...car had full tank.

Performed Maintainance: Replaced fuel filter, checked plugs (OK), wires were replaced a few months ago.

Prognosis: All I can think of now is perhaps the timing is off. Is that possible, for the timing to be off so much that giving throttle will kill but it will idle just fine? Any other ideas? Thanks.

 

air filter maybe??

 

or the flapper isnt moving in the air box

 

Two places top start.

1. What was described as the flapper.....

The device that measures air flow is called an AFM or Air Flow Meter. Its like a flap that rotates through about 90* and changes the voltage in a metering circuit which in turns tells the ECU which sets fuel rate based on how much air is flowing. The flap is called the measuring plate. This plate is completely closed at idle but intake air is not blocked off completely as there is a bypass idle circuit. However, if the flap does not open or is jammed, not enough air will be able to get to the engine to keep it running.
Our vehicles do not have the more conventional MAF with an open tube with a small device dangling in the intake air to measure flow rate.

Remove the top pf the air cleaner and the filter itself. You should see a small rectangular opening an aluminum plate blocking the intake. Try gently pushing the plate to open the intake tract. It should pivot and gradually swing open like a door. If it stuck, there is your problem ... and you need a new AFM. $1000 is about right for anew AFM



If its not stuck, start car and jab throttle and watch what happens to this plate... if it opens then the mechanical part is fine and you really need to trouble shoot it electrically. Search the archives for the FSM which will tell you how to do this.

If the AFM is fine then....

2. Throttle position sensor



It also changes the voltage in an ECU circuit. Try disconnecting it and see if truck will run. If it will, TPS is bad. They are $100 or so.

Let us know how you get on.

David

 

If the above doesn't cure your issues, try the fuel pump.

 

gonna check the timing and TPS this weekend. Everyone here seems to have the same thought...tps or afm....great minds.

 

I posted this in the 86-95 Truckas and 4Runners section for more visibility. See further info there.

"Truck stalls when I hit the gas"