85 Corvette Questions

[ELECTRICMAN1]

My 85 vette runs rough at idle, and is hard starting after she is warm. First start of the day is perfect. The idle "pulses" which can be seen on the digital dash display. As the idle is in the upswing the dash gets brighter, and dimmer on the low side of the idle. I have changed the plugs, wires, distrubter cap. All has helped, but she needs a bit more.

Problem number 2: At the advice of a mechanic, I replaced a fusible link wire form the distributer to the starter as the car wouldn't start. It would crank, but not start. Once I "Jumped" the original link out the car started. Not knowing if this link goes to anything else, I removed it so as not to cause damage. Can you tell me where this link goes? Is it a straight run from the distributer to the starter?

Your help and guidance is greatly appreciated.

V/R,

Ron

[dougbfresh]

Injectors ever been cleaned? What the fuel pressure at idle?

[carsandcycles]

Have you checked your battery cables. Hard starting when warm/hot can be due to extra resistance in the cable, and if the cables are loose or dirty, they may be causing the resistance to be higher than optimal. Pulsating electronics, seen in the dash, might also be due to loose cableing where as the circuit may be routing alternate pathways to reach ground.

Of course it could be a whole lot of other things, but I thought I would throw that one at you, as it's probably the easiest thing you could check and might be the problem. If not, give the guys some more details, and I'm sure someone will come up with alternate solutions.

[dougbfresh]

Sounds more like a leaky injector. He can put a fuel pressure gauge on it and if the pressure bleeds off relatively quickly after the car is shut off.

[justen]

How does it run when you hook that link back up that you removed? Are you getting any engine codes?

[dougbfresh]

Read this, good forum for Vette owners-
http://forums.corvetteforum.com/show...or&forum_id=48

[vetteonr]

That's a good forum Doug. I go there, www.corvettenation.com , www.crossedflags.com , and www.fatherlarryscorvetteshop.com . Those are all good places to find corvette answers.

[ELECTRICMAN1]

Originally Posted by dougbfresh

Injectors ever been cleaned? What the fuel pressure at idle?

Hi Doug,

Thanks for responding to my e-mail. The injectors have never been cleaned in the three years I've owned the car. Currently, the car isn't runninng. (Removed the battery, and it's up on blocks for the winter), so I don't know what the fuel pressure at idle is. The car has been neglected. I'm in the process of trying to bring it back. I had it painted, and I'm in the process of a massive cleaning.

Any tips on how to clean the injectors? Something I've never done. Your help and guidance is appreciated.

Thanks again Doug......Ron

[ELECTRICMAN1]

I haven't checked the cables as of yet. The car is on blocks and the battery is out for the winter. The battery is new, (8 mos. old), and I replaced the battery threaded studs at the same time. I'll get as much info and pass it on once I get the cart running again.

Thanks,

Ron

[dougbfresh]

Go to www.cruzinperformance.com , remove your injectors and send them to him. You get a before and after flow test, new screens and O-rings, all for less than the price of 1 new injector.

[ELECTRICMAN1]

Car runs the same with the fusible link hooked up. I'm not getting any codes.

[Saltmine]

That's all it is......fusable wire.....If you want to duplicate it, you can buy fusable link at most auto parts stores in various amperages. Or, just install a fuse holder in a new wire between the two.

Your '85 Corvette isn't a "Crossfire" throttle body injection system, is it? With two throttle bodies? Those like to blow out the gasket on the plenium cover plate.

I've seen more fuel pumps fail than injectors. But having the injectors cleaned, professionally, is a pretty good idea considering the car's past owners and how it was maintained. Fuel pressure dropping off by more than a couple of pounds can spell all kinds of starting and drivability problems.

[justen]

If I recall correctly 1985 they used tune port injection, Like saltmine was saying it could be the fuel pump, The fuel pump may run fine cold but as it warms up, the pump maybe having some worn out issues and therefore doesn't pump a good flow of pressure like it should. The bearings could be worn down as well. Which would cause extreme friction.

[Saltmine]

90% of the time, the fuel pump is the guilty suspect.

And, true to their "pattern failure", pumps do perform properly when cold, and start dropping off as they heat up.

[danny]

at least the fuel pump on the c4's are easy to change-they're just under the fuel filler door.