2.9 will only go 25mph

[bcoei1]

2.9 runs fine while it is cold. As soon as the temp is up to normal it will only go about 25 mph. Also when you give it the gas, it has a thumping sound. It sounds like it is flooding.By the way it's an '86 if it matters.

 

[Mutant Pony]

Temp sender to the ECA(computer). Also, 2.9s are infamous for bad fuel pressure regulators. I would start with the Temp sensor though.

 

[bcoei1]

I've change pressure regulator, but not temp sender. Thank you for advice

 

[holyford86]

pull codes, instructions on how to do so in the tech library.

 

[abrush]

Well, that is exactly what the first 2.9L engine did that I had in my 88 B2. You are going to want to try to pull codes because I kept replacing everything in hopes of fixing it to no availability. This included both fuel pumps, fuel regulator, sending unit, fuel injectors, plugs and wires, coil, map sensor, compression test and I am sure more that I failed to mention. I ended up determining that my problem was in the cylinder heads. I believe it was bad valves. I never did fix it but instead put a 4.0L engine in. Good luck!