89 merc GM tranny/ sudden acceleration

[DLS]

I'm the proud owner of an 89 GM with 147000 kms, usually runs like a dream, lately having a few problems. If anyone can offer insight, I'd appreciate it!

1. automatic tranny won't shift when driving over about 45 kms/hr (about 28 mph) - after reading the posts, sounds like a valve problem - I've heard these valves are either located inside or outside - makes a difference with the repair cost (too cold here in Ontario to do the work ourselves). Anyone know where this valve is located? I've been driving it short distances in overdrive, without going excessive speed, for a few weeks, it shifts fine while in overdrive.

2. Just started this problem, so I've pulled the car off the road until I can get it in to my mechanic: acccelerator seems to get a sudden surge of fuel - happened three times, twice at about 30 mph, once at 45 mph - I put my foot on the brake but I continued moving forward as if there were no brakes at all - had to drop it into neutral twice, the other time I pumped the brakes and on all occasions, the "stuck" accelerator went back to normal. Thought at first I had hit cruise control because it was as if it was in "resume" position. Too dangerous to drive it with this sudden acceleration problem, but I am hoping it won't be very expensive to repair.


Thanks for any advice out there.

[6502dude]

(1) Valve body is inside transmission. If you have no transmission experience, it is better to leave oil pan on and let shop do the work. How long has it been since fluid & filter change? Many reputable shops will do free road test evaluation.

(2) Check for sticking EEC test relay. Relays are located over passenger side wheel well in engine compartment. Checking relay is pretty tough when car is moving ;-)
However, if you can get problem to occur frequently, you can swap EEC relay with fuel pump relay. If problem goes away - replace orginal relay. If you don't and relay sticks on when car is off, it will drain your battery.

Replacement relay should be about $20CAN.

[DLS]

Hi - thanks for the feedback.

Good news and bad news from my mechanic: the car will continue to drive in regular "drive" but overdrive is going to require a re-build of the tranny. Not yet sure if I'm going to go that route.
I would hate to give up this car, when otherwise it has been a gem. Not sure how long before I will have to rebuild the tranny or give up my old girl. I'll keep my fingers crossed for the best possible outcome.

The accelerator problem was related to linkage sticking - minor repair, got out of the garage with minimal expense.
Thanks for your help.

[fredjacksonsan]

Well it's good to know that you can drive with 1-3 and the trans is sound for those gears; even at 50mph you should be ok, just burning a bit more gas.