300E Starting Problem

I have a 1991 300E with 53K on it. Recently, when I attempt to start it it takes longer to start(2-3 seconds) than in the past.

When it does fire, it quits but starts and runs on the second try. It may stumble a bit before it smooths out and then it runs perfectly with normal operating temps and excellent fuel mileage.

If I depress the accelerator during the starting process, it will usually start OK on the first try after cranking a bit.

The car is kept in an insulated garage in Arizona where the ambient temps inside the garage are in the 90's and outside the temps are well into triple digits.

This seems to occur after the engine has been off for about an hour or longer.

The gasoline is Chevron Premium.

Could this be an 02 sensor problem? I recently had the exhaust changed back of the catalytic converter and the stupid hammer mechanic beat on the pipes coming out of the cat trying to get the old muffler off.

[Alan Robertson]

My post "Starting Problem 1992 300E" of 11-15-2001 may be relevant to your problem.

Classic problem of the 300E. I have not yet heard of a 300E that does not do that (although I am sure there must be some of them hidden somewhere). Mine does it and everyone else's I know of does it too. The prevailing notion seems to be that of vapor lock. Personally I do not mind and decided to live with this minor annoyance, but if you want to fix it, there are many possible reasons some of which are:

fuel accumulator,
leaking injectors,
leaking fuel distributor plunger,
leaking pressure regulator,
faulty one way fuel valves on the fuel pumps,
faulty cold start enrichment valve.

Good Luck.

Thanks guys! I used to live with all kinds of problems with my 318I but I guess I expect perfection from the 300E:-) It'll probably go away when the weather cools down a bit.

I admit to being pretty naive about this subject but I thought at one time that the problem was a loss of fuel pressure. That is, are these cars supposed to maintain the fuel pressure after the engine is turned off? In the past this car started very quickly but maybe that was because the ambient temps were much lower (Minnesota vs. Arizona).

Hey! Their has to be a solution to this starting problem. Car starts fine than dies. Start again stumble than dies. After a few more trys stumble than starts and runs fine. Although won't start at all for a few hours on some days! The 300e is a great car! When it's running! I've done search after search with the same results, ovp, fuel pump relay, check values, temp sensor, spark plugs, fuel accumulator, leaking injectors, have to conclude that it has to be wireing harness or control unit but haven't got that far yet. Anybody have the solution? I've taken it to dealers and they can't fiqure it out. Someday...

[anthonyb]

If your car doesn't start after much cranking, check to hear if the fuel pump energizes when you first switch the key to the "on" position. On my car, it will buzz briefly (less than a second) before cutting out. If you don't hear the pump energize, it may be a shot fuel pump relay that intermittantly fails. I replaced it on my 300e, after successively more often no-starts were occuring, and thus far it has started everytime since (fingers crossed). If the fuel pump IS energizing, then it may be a vapor lock problem...

-anthony

(and, my car does take two cranks to start most of the time..!)

[yal]

Yep two cranks to start here also! Only when the car is warm/hot and has sat for about an hour. Pain in the a$$!
Its not simply ignition because my coil, plugs and wires have been changed. Its not simply fuel because my injectors, fuel pump, fuel pump relay and OVP have been replaced. Temp sensor replaced. I replaced all the above to fix other things and for peace of mind. This has all led to a much smoother, sweeter, stronger running engine which was all worth it for me, but that one starting problem still remains. I'm hoping that I will be able to run a fuel pressure check with my mechanic but I guess the pressure will have to be tested for over an hour. Anyway thats my story so far.......to be continued