Stuttering under heavy acceleration - but only under 1/2 tank

[pcleez]

Hey guys.

I just picked up a 100 in New York on Saturday. I drove it home on Sunday. Everything was going well until I really had to hit the gas at about 60 MPH on the highway. I got stuttering, felt like misfiring (no CEL). When we stopped for lunch I did some digging on here and found the excellent thread on coil packs. Figured that might be the issue and that I would just not push the car too hard on the way home.

Outside of Charlotte on about 1/4 of a tank the truck just started to die. Could barely stay about 35 MPH, could barely make it up a hill. Limped to a gas station. Filled it up. No issue. In fact - if you floored it, no stuttering. Car got down to 1/2 a tank and would start stuttering under heavy acceleration. So, just kept it above a 1/2 tank the whole way home and tried not to hit the gas too hard.

My mechanic is of course slammed with the holiday coming up, and I'm of course freaked out with a broken new truck. It seems to me that the gas level would have nothing to do with a coil pack, so I was hoping someone on here may have some other (hopefully not catastrophic) thoughts?

 

[2000 LC]

Fuel pump?

 

[2001LC]

Sound like^^^. May try a can of 44K to start, but sounds like fuel pump.

 

[camino70]

Why does it sound like a fuel pump? Is it overheating with less fuel around it and exhibiting the failure at 1/4 tank? Are there ways to test it?

pcleez,
I am a bit north of Atlanta, but could try to be available to help replace it some time.

 

[ton504]

I had that issue. It couldn't keep up with the demand after about 20mins of driving. I bought a denso unit from amazon and now I can haul ass.

 

[2001LC]

Why does it sound like a fuel pump? Is it overheating with less fuel around it and exhibiting the failure at 1/4 tank? Are there ways to test it?

pcleez,
I am a bit north of Atlanta, but could try to be available to help replace it some time.

The more gas in tank, more pressure in fuel lines. Fuel pressure is a good starting point since no code (check engine light) and gas level makes a differences.

There may be a simple test without a fuel pressure gauge. Hopefully someone will help out here. IIRC you pinch off a fuel return line. (Edited: Pinching could damage line!) I think it is next to the transmission dip stick, hooked to the engine cover. When you pinch/clamp it fuel pressures goes up.

EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM includes the gas cap. The issue could be as simple as needs a new gas cap. You should here air rushing noise as you remove gas cap. Or could be more complicated component, good luck.

 

[looking4lc]

x2 on Fuel Pump. has similar issue while idling for awhile, replaced it and no issue at all.
cheap insurance to replace plus it seems like it has to be replaced at some point Denso FP and easy 1 hour job.

 

[Manhattan]

pceez, ACC Garage is in Atlanta. If your mechanic is too busy to get to it, Call ACC.