cross fire engine

[Jonney W.]

my 1984 cross fire runs rich when its cold. also it runs kinda rough when warm. sometimes i give it fuel and it will back fire Thur the throttle bodies. has any one ran into this before? my car only has 17,000 miles on it. however it's 29 years old. and still a virgin. the only thing thats been done to the motor is i replaced the plugs and dist cap and rotor and replaced the wires. also i replaced the temp.sensor in front of the motor not the one for the fan. I'm kinda stumbled about this. any suggestions would be great full.

[William C.]

Re: cross fire engine

Several questions, starting with do you have the '84 Service manual? Any codes from the computer? Why the temp sensor replaced? Is the new one an EXACT duplicate of the OEM with respect to input/output curves? How often is it driven? How old is the fuel?

[Jonney W.]

Re: cross fire engine

bill, yes i have the owners manual, no codes in the ecm. i replaced the temp sensor with an updated one from gm its for a 84 two wire instead of the one wire. i read a tsb on this. it's not driven much at all. as far as the gas i don't know how it is. I'm going to suck it out this spring. while I'm doing that I'm going to replace the fuel pump and sending unit. just because of it's age. i wouldn't like to be stranded somewhere. i heard these pumps where bad in the first place. I'm going to use a ac delco replacement unit. I'm wondering if the fuel regulators are bad. this car came from Florida where they use methanol. i have a rebuild kit ome rod chester. that has new regulators in it. i have new gm 84 injectors for it to. it's frustrating because in Ohio the weather is cold and trying to find a corvette mechanic that knows the 84 crossfire is like finding a live person in the Lincoln days.

[William C.]

Re: cross fire engine

Might be worth investing in a fuel pressure gauge do do some troubleshooting before replacing more stuff. Might be a lot less expensive in the long run...

[Jonney W.]

Re: cross fire engine

bill, i have one but i have to modify it to work on the rear throttle body. can i put it behind the fuel filter, and check it that way. if not i have to make up an other fuel line cut it in half and put the gage in between the new line. then take mine off the rear throttle body. Ive check around several places like snap on mac some gm dealers for the fuel pump gage. they just don't have one for the cross fire. tps is in specs as far as the manual goes. i used a volt meter made a set of wires to put my leads on while the connector was still hooked up. the manual said set it to five oms. what is confusing me is there isn't any codes in the ecm. it just keeps flashing code 12.

[Jim T.]

Re: cross fire engine

Jonney how did your 1984 run before you replaced the spark plugs, distributor cap, plug wires, and distributor rotor?

[Jonney W.]

Re: cross fire engine

it ran the same, perhaps a little more rough.

[William C.]

Re: cross fire engine

I'd be thinking the TBI units. They don't like alcohol or sitting a lot.

[Jonney W.]

Re: cross fire engine

bill, thank you for the suggestion. i have the rebuild kit from rod chester for the 400 tbi gm used rod chester for the tbi in 84. i plan on rebuilding them in the next couple of weeks. i have read that some guys will drill out the tbi so they can use a manometer to balance them. i don't know if this is a good idear to do or not. gm cap them off for a reason. besides wouldn't this hurt my chances for a top flight award. by modifying them. jonney