I have a '94 Z28 that has been having some spark and now what I believe to be some fuel issues. Here lately, I typically have to try to turn the car over 2-3 times to get it to start, almost like a dry start at first. Once started, the car runs fine up until it reaches normal operating temperature. Once it gets there, it bogs down real bad and begins backfiring when the accelerator is pressed at all. Another symptom to note is that the fuel pump primes a bit slugglishly on the initial startup, but after reaching normal operating temperature, it seems to prime at the correct speed/rate . The car has also gotten fuel in the cylinder heads twice since these issues have risen. Here is what all has been done to the car and when that would pertain directly to the issues I've been having:

-New opti (Fall '09)
-New plugs/wires (Plugs-two weeks ago/Wires-last summer)
-Ignition coil (Summer '10)
-New cap for opti (Summer '10)

Any advice/input on these matters is greatly appreciated.

Thanks,


Blake

 

Have you scanned it for codes?

Have you checked the fuel pressure?

Operating temperature induced problems can relate to many areas:
-O2 sensors cause problem when it goes into closed loop
-coolant temp sensor problems
-fuel pump overheating
-ICM overheating
-Opti optical cam position sensor overheating

 

Unfortunately, one thing I have not done or had done is scan for codes. I personally don't have access to a code reader or else I'd buy the OBD1 cable I'd need to scan her :/

 

I'm gonna just go ahead and change out the fuel pump, it's been priming funny so I know that the issue is within the pump (it's obviously getting voltage because it's still priming so that's a moot point). Found a Walbro 255 on Amazon for a $100, once I get a few bills taken care of, gonna scoop it.

 

Make sure it's a "real" Walbro. There have been reports of cheap Chinese counterfeits.

 

Good to know, I'll be sure to check that out. Is there some sort of specific seal or mark of authenticity I should be looking for?

 

Bought a fuel pump with sending unit off a guy on here who's parting out a Z same year as mine, should be in tues or wed.

 

Pump arrived yesterday afternoon, took a little longer than expected but it's here. Gonna try and get it switched out sometime this week.

 

Update, checked fuel pressure. 41 psi when ignition key was turned to "on" position (not started), during idle she held right around 36 psi. Fuel pump fuse in driver's side fuse block was fine, bought an OBD 1 scanner at auto zone for $30 and attempted to scan for codes, but wasn't able to pull anything. I know I currently have a code for my inoperable air pump (the SES light comes on during drving still, code was found by my mechanic), so why wouldn't I have been able to at least pull that one?

 

A "$30" scanner is typically one that simply shorts the pins in the ALDL connector, to flash the DTC codes on the SES light. Will only work up to the 1993 LT1. For those, you can do the exact same thing with a 1-cent paper clip. The scanner you got was probably an Actron, and it says right on the label of the box it will work on a 94 - but it will not.

For your 94, you need a real OBD-I scanner to pull the codes. They cost more than $30. The alternative is free scanning/data logging software, and a cable to connect to a laptop.

http://www.ttspowersystems.com/DataMaster.html

http://www.andywhittaker.com/ECU/Fre...0/Default.aspx

http://www.akmcables.com/

 

Yeah, Fred, it is an Actron. Do I feel like a moron for buying that stupid thing now

I was trying to avoid having to buy the cable but I may go ahead and do that. Just depends though because my buddy's tuner, who is about 45 min from me scans OBD1 for $10. I'm leaning toward going that route if getting that fuel pump on makes her roadworthy again, I need a good street tune anyway.

Thanks for the links, Fred.


Blake

 

Your fuel pressure seems good enough to me. I would be skeptical that changing it would help.

 

You don't think so? Even with the sluggish/weird sound my fuel pump has been giving off when priming? It seems to me that it's on the way out and is gonna need changed anyway, it never did that before I already have a replacement pump and I'm getting to be at a loss with this car on what's wrong with it

 

Well the new pump is on, same symptoms remain as before. Tried the paper clip trick to read codes and that didn't work either, anyone have any ideas?

 

You can't read codes with a paper clip past 1993. You need a real scanner. You tried the $30 paper clip and it did not work. I think Fred already covered that.