Acceleration stops abruptly when compressing pedal more than 50% of the way

[nbarb]

Hi forum,

Been running into an issue with my jeep after coming back from a week long vacation.
Was driving fine on the highway for about 40 miles then suddenly couldn't create power anymore. Sounded like a faint whistling coming from the engine block area. Letting off the power for a few seconds the whistling stopped and I was able to continue driving as long as I don't compress the pedal >50%.
Limped it home and have been using it for short distances since.
Got a CEL code for bad TPS sensor voltage once the issue started, replaced the TPS with an Autozone one (i know, but I had to try something) and issue persisted but CEL went away.

Ordered a new fuel pump -> Gets here in 4 days. Thinking the whistling is a lack of pressure in the fuel system, letting off the pedal allows a walking wounded fuel pump to gain slight pressure. Pushing the pedal down hard releases the pressure in the fuel system and causes whistling / lack of power.
Cats are brand new since I got rear ended in March and my exhaust was crumpled.
Refilled my fuel tank earlier today -> Issue didn't improve or change at all

Anything else I should try while the fuel pump is on the way? -> Thinking I could try cleaning out the fuel pump exhaust tube, not sure where that is though.

Manual, 1997 sport, 4.0, 32" tires, 238k miles, 2.5" lift. New 4.0 engine with 78k miles. Stock trans

 

[macleanflood]

I wouldn't rule out the cat. New parts are all shit.

I'd test your fuel pressure before replacing the assembly.

I'd pull the O2s and create and exhaust leak to rule out the cats.

And wiring... grounds.

-Mac

 

[JKP]

A weak coil will cause the engine to cut out under heavy load or high RPM. It usually gets worse the hotter the coil gets. My YJ would allow me to drive down to our hunting lease with no problems, but after heat soaking, it would start cutting out under load on my way home. It would cut off cleanly when it did and would restart itself with the manual trans when I let off the gas.

Get a fuel pressure test gauge and verify your fuel pressure at idle and then when you rev the engine. It's available as a loaner tool at most parts store. When my fuel pump on the YJ was weak, it wouldn't cut off cleanly, but would stutter just like hitting a rev limiter until I backed out of the throttle.

Stay away from store brand Chinese coils. The only one I found that lasted was the Blue Streak by Standard Ign. Even the MOPAR is made in China.

 

[nbarb]

Seriously facepalming at this point. Went under to check engine grounds and spotted this. Issue resolved.

 

[macleanflood]

The only one I found that lasted was the Blue Streak by Standard Ign. Even the MOPAR is made in China.

I used a Holley Accel on my 97 and it's been fantastic for almost 2 years on my 97.

-Mac

 

[JKP]

Maybe they've made a come back. I had Accel coils on cars and Jeeps back when they were made in the US. I had a US Accel on the YJ forever before it blew, then found everything had moved to China. I went through a MSD, MOPAR, store brand, etc with each lasting weeks to months before finding the Blue Streak. I think the engine heat was killing them.

 

[macleanflood]

I would imagine MSD and Accel are exactly the same product these days since they're owned by Holley.

I probably got the lucky one.

-Mac

 

[JKP]

Yeah, I've wondered if they are the same. I blew a MSD within a couple of months, IIRC.

 

[TEZZA]

Seriously facepalming at this point. Went under to check engine grounds and spotted this. Issue resolved.

View attachment 549462

That sucks!

 

[99greenTJ]

Seriously facepalming at this point. Went under to check engine grounds and spotted this. Issue resolved.

View attachment 549462

Please describe what the pic is showing?

 

[Harold&Cat]

The ring imprint on the insulation implies that the intake to the air breather was blocked , therefore restricting airflow into the air filter box .

 

[99greenTJ]

Thanks