C4 Fuel Issues

[budammo]

Hi Need some help. I own 1989 C4. The car run rough at idle and
sometime will not start. The car has all the original parts on it - ie fuel pump, fuel pump relays, etc. Fuel presurre at start up is 41 lbs with the key on and 38 with the car running. Started right up this morning but rough at idle. Has anyone had this problem?

[Mark Dalton]

Howdy and welcome to the site. I can't help with your fuel issue but I'm sure someone will be along shortly who can. You might also jump over to the welcome forum and say hi. Most members check there looking for new folks.

[Pres712]

My '86 is starting to run rough and the milage is dropping. Jump on over to "Maintenance, Mods and Tips" where "Skakedowns067" has some knowledge of a good place to buy some fair priced injectors. I just sent in an order for a set.

[Shadow]

We have three vendors on the forum that may be able to assist you as well.

Mrs. Extreme, Ms Antivenom and RevXtreme,(Dang it! I know there's another one here, but it's a newer shop and I can't recall who it is?), all are performance shops,the first being up toward the panhandle/Tallahassee area, the second being in Seffner (near Tampa/Brandon) and the third being in the Bradenton/Sarasota area.

You may want to shoot a pm to one of them and see if they can help you? Yo'll find the people on this forum always readhy to assist any way possible.

An check with Shakedown as mentioned Good guy, lot of good infromation on the C4.

Good luck with the issue and welcome to the forum

[gmjunkie]

Your Fuel pressure is Great,Check for cracked vacuum lines/leaks and carbon in EGR!! Check out the Distributer cap/Rotor/Plugs and Wires!!If all checks out then maybe give Jon Sr. or Jon Jr. at FIC and call,their Both Great,Knowledgeable guys and sell only Quality products!!

Tell'em "GMJunkie" from Old Fort NC sent you!!

[budammo]

Originally Posted by gmjunkie

Your Fuel pressure is Great,Check for cracked vacuum lines/leaks and carbon in EGR!! Check out the Distributer cap/Rotor/Plugs and Wires!!If all checks out then maybe give Jon Sr. or Jon Jr. at FIC and call,their Both Great,Knowledgeable guys and sell only Quality products!!

Tell'em "GMJunkie" from Old Fort NC sent you!!

Thanks for your help! I already changed out all the vacuum lines, distributor cap, wires, plugs, rotor, coil, Ignition control module and fuel filter. Next I am going to replace the original EGR valve. I cannot understand why the computer is not putting a trouble shooting code. I took it to the chevy dealership and they say I need fuel injectors but none of the injectors are leaking. I am going to replace the EGR tomorrow. Again, thanks for the help.

[RevXtreme 1]

I'm willing to bet you have a few fuel injectors barely working. Take it to Greg at Anti Venom and he has a fuel injector/flow matching unit and can show you if they are bad or not.

[budvette]

my bet would be injectors,check resistance of all injectors should be close to the same on all . 15 to 17 ohms if i remember right . mine ran rough with no codes found 3 bad runs good now.

[shakedown067]

Yeah, those multecs injectors are junk and don't need to be leaking to be bad. They are a known issue with the L98 engine. Greg at AntiVenom can certainly verify that you've got some bad injectors. For all the injector info you could ever want, check out fuelinjectorconnection.com or visit their youtube.com page to see how bad the multec injectors flow.

[budammo]

Originally Posted by shakedown067

Yeah, those multecs injectors are junk and don't need to be leaking to be bad. They are a known issue with the L98 engine. Greg at AntiVenom can certainly verify that you've got some bad injectors. For all the injector info you could ever want, check out fuelinjectorconnection.com or visit their youtube.com page to see how bad the multec injectors flow.

I am getting 25-miles per gallon, so I do not think the fuel injectors are bad, but I maybe wrong. Thanks everyone for you're help and I will get back with you all once I figure it out.