After some help from members of this forum, I was able to diagnose a couple of problems with the fuel system on my '87 Trooper. I rebuilt the carburetor and replaced the fuel pump** and was able to get it running after increasing the idle speed (only to ~1000rpm).

A previous owner or mechanic drilled out the plug on the idle mixture adjustment screw. Can anyone advise me of a way to adjust the idle mixture without taking it to a shop?

Thanks for your help.

Martin


** The mechanical fuel pump was a pain to replace, but by removing the EGR valve (?) it was at least possible.

Hey Martin , turn the mix screw all the way in with the eng idoling and at normal eng temp , it may start to stumble if it does stunble or start to die back the screw out just a little at a time no more than a 1/4 turn let it stabilize and then another turn until the eng speed starts going up, at about 1 3/4 turns from the inward seat , the eng will start to slow down again now turn the screw back in clockwise bringing the speed back up and then turn it in just enough to drop the rpm 50 rpm and then set your curb idol speed to around 800 rpm and you should be in good shape Jerry

Jerry,

Thanks for your help. Unfortunately I couldn't tell much difference in the engine speed when turning the idle ajustment screw. I may need to remove the mixture screw and make sure it is clean (I didn't do that when I re-built the carburetor - I was trying to minimize affecting adjustments - bad idea I guess).

I'm still trying to tweak the carburetor a bit. Currently it's running rich. I THINK (& hope) that I simply didn't ajust the float properly.

Also, I don't know if there is a direct effect, but it seemed to run worse after replacing a leaking exhaust flange gasket just upstream of the catalytic converter. I understand that if it's clogged, the vehicle would run poorly, but it shouldn't cause a rich mixture (I don't think).