87'5.0

First a little info, I have a 1987 lx 5.0 that has been converted to mass air off an 89. This problem has only occurred twice but in first gear at about 4500 rpm the car just completely falls on it's face. But right after that happened I got on it again and it pulled harder than it ever has. Any ideas, thanks.

88 orangepeel notch

Welcome to the forum.

I'd start by pulling codes, see if any are there that may point you in the right direction.

Then start looking at your fuel system, plugged filter, regulator, pump, lines, etc.

And just to clarify, this only happens in 1st gear ?

87'5.0

Thanks, fuel filter, then fuel pump was the next route I was going to take.

87'5.0

Sorry, yes it only happened in first gear, it's only happened twice. Also like I said right after it happened I got on it again and it pulled harder than it ever has.

88 orangepeel notch

OK, don't just start throwing money at this without verifying. If this only happens in 1st gear, I'd rule out the pump. The filter is cheap and easy, and probably needs the be changed anyway.

And definitely pull codes before anything, it's free and easy, and could save you alot of headaches.

87'5.0

I tried to pull the codes last night, but either there wasn't any or I wasn't doing it right. Do you know what color the self test input wire is, because there are two wires that look like it. One comes off the same harness and the other one comes off a harness right next to it. Maybe I wasn't using the right one. Or my check engine light might not be working.

87'5.0

I think I have valves going out, I did a compression test and had 0 psi in two cylinders

87'5.0

I can't believe my car ran as good as it did like this. It would still break the tires loose in second and chirp them in third.

88 orangepeel notch

Wow, good idea on the compression test.

Now, just imagine how much better she'll run with a good head gasket.