VERY hard starting - Cold

[perfimage]

Ok, I have had about enough of this and need some feedback.

93 Z34 Lumina with 140k miles. Timing belt changed 20-30k miles ago. This thing runs GREAT!!

The problem I am experiencing is that after the car sits for more than 2 days without being started, it is VERY hard to start. It backfires through the intake and exhaust and acts like an old "flooded" carbureted motor (not "catching" at all then finally "catching" but still requiring the starter to keep it turning and finally speeding up and starting. There is also a strong odor of unburned fuel and I had a fire in the intake the last time this happened. It also backfired bad enough that it blew my air cleaner assembly apart, so I am sure there is plenty of spark!

Let me say again that this happens ONLY when it sits for more than 2 days without being started. Overnight cold starts are no problem, warm starts are no problem and when the problem occurs, once I get it started, I can shut it off (before the engine warms up), let it sit overnight and go back the next day and it starts right up. And again, once started it runs PERFECTLY and doesnt seem to have any performance issues.

I am getting only a Code 53 (EGR), but have gotten this code almost since the day I bought the car and teh problem has only appeared in teh last 6 months or so.

Any ideas?

Thanks!

[DEI37]

Kind of sounds like leaky injectors, or something like that. But, I would THINK that something like that would manifest itself as a problem in less than two days like that.

[perfimage]

I thought the same. I even spoke with a local shop that does custom fuel injector installations and he seems to think I need to replace the injectors (not clean them). I was thinking about sending them off to get cleaned, but am not sure it will help. At the same time, it is awfully expensive to replace the injectors and the results posted in this forum after having injectors cleaned seem positive.

Another symptom I forgot to mention is very erratic fuel mileage. I drive this car daily, M-F on the excact same route. My mileage varies from a low of 17.3 mpg to a high of 21.1 mpg with the norm being ~18.5 mpg using the same gas from the same station etc. To me, this also points to leaky/worn/dirty injectors...thoughts? thought I annnot say for sure, it seems that the problem began appearing more often at about the same time I noticed a decrease in mileage and more erratic mileage figures.

Thanks Again.

[gpse3400]

You might want to try a fuel pressure test... soudns like the regulator is leaking down and pulling fuel through the diaphragm.

The EGR passage is most likely clogged. Carbcleaner and rigd yet flexable tool with elbow grease will clean out th epassage...

[perfimage]

Fuel pressure and diaphragm leaking sounds logical. How exactly would I perform this test? Is there a "how to" on this site?

Thanks.

[gpse3400]

You will want to get a fuel pressure tester from the parts store, for sale or rent. The fuel pressure fitting is on the fuel rail on the passenger side of the engine, you might have to remove the cosmetic cover on th engine to get at it, I dont rememeber. There is a test to perform. First you'll need to bleed the fuel rail of any remaing pressure which will probably be not a hell of alot. Get a screw driver and a towel.Place the towel around the fitting and use the screw driver to push in the valve and fuel will come out. Make sure have the towel in a way you can catch the fuel. Screw on the pressure tester nice and tight. Over by the battery you will see a red wire with a plastic casing oin the end. That is the fuel pump primer. take the end of that and touch the positive terminal with it and th epump will activate and prime the fuel rail.wen this happens note the fuel pressure on the tester. 41 and 47 psi pump running is the range. Pump off it should drop a few and hold steady. Then start the engine, the pressure should drop by 3-10 psi at idle.

A if you pressure doesnt hold after th pump shuts down your regulator or fuel pump or fuel pump pulsator is at fault and I will tell how to diag that later.

B if you start the engine and the pressure doesnt drop accordingly, you may have a bad vacuum connection or a sticky regulator.

[Sonyman]

where is the fuel pump pulsator located?

[gpse3400]

The pulsator is in the fuel tank on top of the pump.

[Sonyman]

is it that thing thats inbetween the outlet tube of the fuel pump and the tube that goes through the sending unit...kind of like a rubber muffler

[gpse3400]

Yeah its got that metal casing on one side with the double bumps.

[perfimage]

Thanks for the info!

I am off work next week and will try to hunt down a pressure tester and test this. Once I do I will post my results.

RED