Fuel System Stumped Celica Dealership - HELP

[LexF15]

Need some help with my 1990 Celica ST. Yes I realize it's an old car, but as most of you have probably enjoyed it's been very reliable. About 2 months ago it started to have some acceleration trouble on the first start of the day. Then it became every start of the day.

Specifically, in second and third gear, as I get to about 2800 RPM, the car stops accelerating. I can put the pedal to the floor with no change in RPM, but I can maintain the speed where it happens. It has also happened in first gear, and rarely in fourth. Of course by the time i'm in fifth gear I'm usually pretty high on the RPM and haven't noticed it there.

The car is a 1990 Celica ST 4 cylinder 1.6 liter manual transmission. I've owned it since 1992 and have taken great care of it since. Miles are 147,000, so still young by Toyota standards. I should mention the car was in storage for 3 years while I was in Japan in the military, but I've had it out for 5 years now and this is a recent problem.

What the dealership did over the month that they had it:
First they cleaned the throttle body - they said there is a known issue like this. No fix.

Then they thought contaminated fuel (so did I) and cleaned the fuel system forward of the filter, and emptied the gas tank. The in-line filter was still good, but they replaced the main filter. I didnt know there were 2 but I'm not mechanically inclined. No fix there either.

Then they thought fuel pressure or volume. Volume is within spec and pressure is slightly high but also in spec they said. They checked pressure with the car driving and in idle.

Then they said the 99% fix was replace the fuel injectors, and looking at the old ones, I agreed it was a good idea. After changing all 4, the problem remains, although I certainly have more power available, the failure to accelerate is still common and fairly predictable.

Can I accelerate out of it? Not by stepping on the gas. What happens is the RPM stays, and may rise slowly before BAM - instant RPM and the car leaps into acceleration. What I typically do when it happens is upshift, and slowly accelerate until I hit about the same RPM where it happens again. Then I upshit again. It's a slow process where I'm never in the meat of the gear for good acceleration, and can be dangerous in certain traffic.

1500 dollars and one month in the shop and I have the same problem. The dealership is here in Montgomery AL and they are stumped. The rest of the car is fantastic, with a new paint job, new brakes, battery, ball joints, and religious oil changes. I hate to give up this car for this one small thing. The last suggestion the dealership had was the computer. By the year of 1990, you can guess it's an older computer, but they had no faults with it. Of course the older computer doesn't provide all the fancy data the new ones do so it was hard for them to be confident. Really really looking for some ideas here - I love this little car, and just to TRY a new computer could cost 4 digits since they aren't just lying around. The big stumper is that it doesn't always happen, but when it does, it's always around that RPM.

Thanks in advance!

[19Celi87]

Hmmmm. . .
Just ideas because we don't know the guysin the shop.


TPS is hitting the fuel cut to soon. Computer figures this out and ignores the signal. Takes a sec or two but then you go.
All cables are out of adjustment.
Speed sensors including Speedometer on in the dash. ( Two all together.)

Really hard to say w/o seeing it. Then it would be harder. . .

If the shop could not get it either:

1. Get a new shop.

2. Get a manual and spend a year going over it slowly?


Hope you nail the prob. soon.

Good Luck

[indianboy7]

I had the same problem with my 85 MR2 a while back...it turned out to be a combination of the fuel pump and the tps........i'd also replace the other fuel filter...can't hurt....

edit:....you might also check the vacuum lines........i found quite a few that leaked on my MR2 and when I replaced them, it fixed a lot of problems....

[LexF15]

Thanks fellas - I'll have to look at that stuff - particularly the vacuum. They swear up and down the pump is good but might be a cheap thing to swap out versus a new computer. I'll forward these to the Toyota dealership and see what they think - please keep the posts coming - your past experiences can save me some serious pain and dinero.

Going to leave this with another shop over Xmas, so the more ideas and the sooner - the better. Thanks again.

[LexF15]

Oh 19Celi87, the TPS is brand new, and it's not like it just takes a second or two and then you go. You could be stuck at that RPM and speed for 15 or 20 seconds if you don't do something like downshift to get high RPM or upshift to crawl out of it from low RPM. I'm equally stumped. Appreciate your help.