Hello,

I have a 1990 F150 502 that is giving me a fit. Please chime in if you have any good advice.

Problem:

When slowing down coming towards a red light and the light turns green, I accelerate from around 20-25 mph, truck will buck and jerk similar to newbies learning how to drive a straight drive and dont quite give it enough gas and it bucks and jerks.. just to give you an idea of feel. The rpms stay steady, so was thinking not slipping in tranny.

I have thought all along was fuel starved. Truck runs great otherwise!

What I have already done:

Plugs, wires, fuel pump in both tanks, green fuel relay and tps.

 

Any codes?

 

What is a 502????

You changed the plugs and wires - what about the rotor and distributor cap? Fuel filter?

 

no codes

 

Oops, just saw that, 302. Yes cap and rotor at time of plugs. fuel filter is less that 10k miles so are fuel pumps. changed fuel pumps due to senders bad, was cheaper to do whole assembly than just sender since i had the bed off.

 

Look for vacuum leaks.

 

Might be the MAP sensor.

 

Check the module on the side of the distributor.

 

Thanks all. I have replaced map but been a few months ago and not for this problem, I am currently checking vacuum leaks and with hit the module if no leaks found.

 

Check the fuel pressure with a gauge. Unfortunately, brand new pumps can't be relied on - they often fail. Especially if they weren't the more expensive ones.

 

Had the same symptoms with my '92. I'm guessing you have an automatic trans? Is it shifting really hard?

My problem was the Torque Converter. It became unbalanced over time and made the whole truck shudder.
Everything was fine at highway speeds.

I had a shop balance the Torque Converter and all was good. Also had them change the transmission front pump, and rear main seal while they were mucking with the transmission.

For reference, my truck had 185k miles when this was going on.