i have an 86 trans am now with a 305 with just under 200,000 on the clock.. in the process of putting together an l98 for it but need this car to last til next spring.. my 20 amp ecm fuse keeps blowing.. in addition my alternator is acting irradically and will drop to like 10 volts when at a stop light.. then when i go it goes back up.. when i get on it a lil bit pop goes the fuse .. already gone threw like 10 fuses in a week.. will it be bad if i put a 25 instead of the 20?.. i had to use one for like 3 mins to drive home when i ran out of 20's .. someone said that the alternator might be sending too much power to the ecm causing it to blow.. could this be the problem?..

 

Not sure about the alernator sending out too much power. Sounds like you might have an intermitent short somehwere in the wiring. First thing is I would check all the wiring on the car.

Not much of a help I know but with things like this it is very hard to pin point the problem.

Test the alternastor with a voltmeter. Start the engine, turn on the lights, fan etc to draw as much current as possible and see what the volts are. They should be definitely over 12.5v most likely over 13v. 12.5 is no good really so they should be above 13v.

With no accessories running the volts should read above 13.5 roughly.

Check the fan wiring too and the fan relay.

 

a local mechanic told me to pull the fuel pump relay to see if the fuse blows after i turned the key. i pulled the relay i turned the ignition to on and the check engine light came on today i replaced the relay.. pop the fuse.. so i guess i am in for the big fuel pump job.. and easy methods to do this?

 

Why not just replace the fuel pump relay since you have mentioned earlier that it was falling apart and you had to tape it together. Beats pulling the gas tank and changing the pump and then finding that wasn't the problem

 

no change. put the new relay in. turned the key to see if the pump primes nothing .. pops the fuse.. ive heard of people cutting a small hole in the rear section of their car to get at the fuel pump is this safe and how is it done?

 

Trust me, you really don't want to do that! A small hole won't be enough; you'd have to really hack it up to make a hole large enough to do any good.

IMHO, dropping the fuel tank on a thirdgen isn't as big a deal as some people make it out to be. I've changed like four fuel pumps now, and while an F-body is not the easiest car you'll ever find, it's not that hard either. The trick is to get the car high enough so as to have enough space to rotate the tank as you raise or lower it, so you don't have to bend the fuel filler neck. Some nice tall 6-ton jackstands will do just fine; no need for a lift. Disconnect the shocks and brake line clip, so the axle can hang down really low, and get the exhaust out of the way (my cars, you can just remove the right rear spring, and tire, unbolt the cat flange, and slide the exhaust over to the side).
Only real hassle IMHO would be if the FP failed with a full tank of gas, it'd be a little bit of a PITA to siphon out enough to reduce the weight of the tank to where you can manipulate it easily.

There is a writeup at http://www.89tta.com/fuelpump.htm
I don't completely agree with everything in it (like bending the neck), but it's worth reading.
I'd also expect you can find some more tips by searching the other forums here on TGO.

 

Get rear ended hard enough to crumple things, and you might have a bunch of gas inside the car with you. I like solid firewalls between me and the gas tank.

 

HERE is something I did that helped a TON.... it took some maneuvering to remove mine the first time..I rushed and broke the filler neck...10 bucks later it was welded and fixed for life...

ANYWAY while the tank was out I took the hole that the filler neck goes through and Opened it up all the way flush with the subframe( im talking the inner hole by the frame not the gas cap hole)***it sticks up about 1" from it as it was...I made 2 slits and bent the metal over onto the frame and welded the metal down.... Anyway that extra 1" of clearance made the reinstall and ALL future removals a snap.... It did not hurt the integrity since I bent it over on the frame and welded it at the corners...

what it did was give more room and removes the LIP that the thing hangs up on....

I could have went a step further and removed some metal from the top BUT it is soooo easy to remove now that there was no point..

Sorry but I did not take pics...