Hello all,

I wanted some input as to how to proceed here.

I was traveling down a tollway in Oklahoma with a speed limit of 85 at that speed and all was fine. Call runs and idles at a good .95-1.25 RPMs, recently had injectors cleaned. All was running well when suddenly I felt a change in the acceleration. The throttle became 'all or nothing' so to speak - fuel was not or only barely being delivered when I let off the accelerator ever just a little but when I was pressing very firmly, it was getting a lot of gas.

The result was that the only way to keep the car running to accelerate heavily. Because that is obviously a problem, I exited at the first chance I could safely. As I exited at the car shifted down to normal speed, the engine died for fuel starvation, battery light came on, power steering went out.

Attempted to restart several times failed. Electrical was sparking strong and engine cranked sufficiently but there was not sufficient fuel delivery.

I tried turning key to II with transmission in D to let fuel pump run to prime and pressurize system - that failed.

I tried hitting the fuel pump to move or breakup anything I could move out of the way and that didn't help either.

On some tries, I could get it started by pressing very heavily on the accelerator. When it did start, it had the same acceleration problem - it would only run if I would give it a lot of gas with the accelerator and the throttle felt 'all or nothing' in that it would not allow a steady, slow stream of fuel only a forced delivery of a lot of fuel or an amount too weak/little to keep the engine running. When it did run, it ran VERY roughly, causing the car to shake and . Because it was so rough, I turned it off and waited.

After waiting for the person I had called to come assist me for about 2 hours, I attempted to restart the car. It started perfectly and idled evenly at the usual .95 RPMs. I let it run for about 10 minutes and acceleration in park felt smooth and normal. I then continued the drive from Oklahoma to south Texas (about 310 miles), attempting to keep the speed/acceleration as smooth and even as possible around 65 or 70 with no problems and without stopping.

Since then I have driven the car around town 2-3 more times for about an hour or so each time and have had no further problems with it.

I plan on replacing the fuel filter and seeing if there is any noticeable improvement but given how sporadic and unpredictable the symptoms have been, it will be hard to know if I have fixed anything with any certainty until I have another breakdown (or not). Any similar experiences or thoughts?

 

Hi there, I had two similar issues. One went away and one I fixed. The first was a lack of fuel, it's good to remember that the throttle only let's in more air and doesn't directly control the fuel supply like a carby engine. I'm just assuming you have efi.

The pump had become blocked and by cycling the power to the pump I was able to get it dislodged. I couldn't get the pump to go with the key in position 2 so I just used my jumper cables to connect the battery direct to the pump. I'm going to install a fuel filter between the pump and the tanks to avoid this again.

The second issue was very similar to your starting issues and having to have the throttle wide open to keep it running. It turned out that the plastic connectors on the injectors felt snug but we're not properly keeping contact so I was sporadically losing cylinders and power. I replaced them and all good.

I'm not an expert but that's what I've come across with similar symptoms.

Cheers,
Harry

 

Empty the contents of the old filter into a clean jar. What you see might dictate your next steps


Yes, it can be difficult to diagnose and treat symptoms when they're sporadic. Often it become process of elimination rather than actual diagnosis

Is the ductwork between the Air Flow Meter and the throttle body in good condition, and secure?

With the engine running gently wiggle the wires at the coil, the firewall relays, AFM, ignition switch. If the engine reacts, you've found your problem.

Are the ground wires at the rear of the water rail in good condition?

As a guess....but a fairly educated guess....replace the ignition module and oil. AC Delco part number D1906. I like the Lucas DLB170 coil.

Cheers
DD

 

Yeah, as to the ignition switch. Mine gave me no end of issues.
I replaced it with a good one from David Boger. a world of difference in the "feel" of the two. Mine was loose and sloppy, his nice and tight.


I took the old one apart and t was a mess. Missing little ball, or I just lost it.


As much of these cars functions are switch powered, a poor one can screw up a lot and sporadically!!!


Carl

 

Thanks all - I will update this week once I replace fuel filter and check the contents.

I should clarify when I say putting the key into the II position in Drive failed to do anything, the pump was running properly and turning on as it should, it simply failed to resolve the no start- poor running issue I'm describing.

I did check the AFM meter and all air flow connections and they were tight and secure, no problems.

Like I said in original post, I recently had injectors clean so given my propensity to suspect what was most recently changed, I had the injectors cleaned recently so Harry, I'm thinking that the connectors on the injectors are indeed a good place for me to look to solve this problem because as I said, my car is running very strong and smooth when not presenting this throttle issue as well. Thanks for the idea.

I checked the ground wires, AFM, all firewall connections, and the ignition switch and reachable ground connector wires once I got it started and it was running smoothly again (mostly out of a hesitant fear that I would get back on the highway only to have the problem strike again) but the car made no response and any of those wigglings.

I'll proceed in the order of: check fuel filter, air filter, check/tighten injector connections, then ignition switch and coil and re-post when complete with results.