Hesitation / Throttle Response spotty - Bad Fuel Filter?

[6SPD]

Hello R3V,

Currently driving a 1987E. She's been running like a champ lately with 212k on her. However, the other morning en route on commute the other morning the gas pedal basically lost all responsiveness. There was no longer a punch of acceleration when I put my foot down but a slow, painfully slow throttle input instead. I limped the car home and got a ride to class from a roommate. Let the car sit for a day because I didn't have the time to dive into it. So here I am. Just ran the car for a while parked, started fine, idled fine, once it warmed up a bit it sounded like it was starving for fuel (the feeling you get if you slip the clutch to slow and are about to stall). It came and went then idled fine. Took the car out in the neighbor hood punched down the throttle to find good acceleration and then it bogged down and lost its responsive ness.

The issue comes and goes. I have a feeling it's the fuel filter or could it have something to do with the intake system?

Looking for some quick insight so I can get the right parts ordered ASAP.

Cheers,

D

[jlevie]

While the filter may need changing, I suspect there are other problems. I would expect fuel delivery issues to get worse with increasing engine speed and load, ultimately completely starving the engine. Change the filter and see what happens.

[wenbeaver89]

cracked intake boot/vacuum leak? Sometimes when the rubber heats up it flexes a little more and opens up the cracks more! Just something to check!

[Ryann]

Swap your AFM with a known good one.

[TobyB]

and meter your TPS, and measure your fuel pressure!

t

[shaferbm]

Is metering the tps outlined in the bentley manual?

[6SPD]

What is the TPS?

I'm currently up at school in Santa Barbara with little to no tools. Probably going to take it into a shop on Monday regrettably (If I can limp it there, it's that slow and unresponsive right now).

At least SB has a reasonably good public transit system for students

[6SPD]

Swapped the fuel filter that just arrived in the mail. Started her up and it seems to be running at 85-90% I'd say. Which is a hell of a lot better than how it was limping along this morning.

[shaferbm]

Throttle position sensor. It is the black plastic box with 1 plug attached to it, and is located underneath the throttle body. To answer my own question, it is outlined in the Bentley manual on page 228 (of the bentley .pdf at least)

[mcaden]

Rust in fuel tank clogging pick up? Were you running low on fuel when it happened, maybe a 1/4 tank left?

[6SPD]

Rust in fuel tank clogging pick up? Were you running low on fuel when it happened, maybe a 1/4 tank left?

California car, almost a full tank when it happened.

[matthugie]

Rust in fuel tank clogging pick up? Were you running low on fuel when it happened, maybe a 1/4 tank left?

California car, almost a full tank when it happened.

California car has nothing to do with it. My car doesn't have a speck of rust on it and I just had to replace my tank due to it rusting on the inside. This usually happens when cars sit for a while and get moisture in the tank.

If what came out of your filter when you changed it was brownish then you might have rust in there. Pull the pump and look in the tank. A mirror is handy, but you'll probably be able to tell without one. You can also change the fuel pump sock, if you have rust that will also restrict fuel flow.

[6SPD]

Fuel didn't have any nature of browness coming out of it when I changed it.

The issue has seemed to come back. Especially when I start the car, it idles low around 500rpm and the engine sounds starved and has a chugging sound to it. Once it idles for a moment or two it warms up and idles alright. Drove the car from Santa Barbara to La and back and it happened both times when the engine was cold.

[ParsedOut]

Fuel pump is my vote.

[Cletonius]

You may want to replace your fuel pump relay. My car smoothed out a bunch with a new relay, the 20+ year old one must not have been making good contact anymore.