I'm new here guys and I need a christmas miracle. Here I am at my shop on Christmas eve, trying to diagnose a hard start problem for a college kid who is only in town for the holidays. The car is very hard to start cold. He had this problem last winter, but just delt with it. During the warmer months, it starts fine. But with temps below 65-70, hard to start and once started, blows blueish fuel smoke from exhaust. Once it warms up the car runs fine. Another shop has already replace cold start injector and coolant temp sensor. I replaced spark plugs yesterday...they were fuel fouled and corroded. This made no difference. I believe in miracles...can ya'll help me out?

I've always been under the impression that blue smoke signified oil; not fuel.

Couple things you can do:

The EHA (Electro-Hydraulic Actuator), a black fuel pressure regulator located on the side of the fuel distributor, can be adjusted a bit richer to compensate for fuel distributor wear, and then adjust the CO a bit leaner. You can also unplug the cold-start valve to see if this helps startup. EHA adjustment is a bit complicated (you measure pressure differential and remove/adjust EHA 2-8 times before you get the adjustment right-on; I'll look up and post the specs Saturday the 25th). I'm assuming a ton of miles (college kid and all...)?

If this doesn't work, give him a 3mm allen t-handle and a can of starting ether for Christmas, and send him on his way for another year.

Valve seals would be a likely cause if it is blue smoke, and enough oil could foul the plugs at lower temps to cause run problems (I've seen it before, anyway, lots of times...). Of course, I've also had them come in needing guides as well, but normally, they give you a rough start when warm as well.

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Don't ask me, I'm a shop-owner by default

Normal differential pressure on KE-jet engines w/ EHA is .4 bar (5.8PSI); adjusting it slightly higher (.45 bar/ 6.5PSI) will allow for fuel distriburor wear on high-mileage vehicles. I have found that your first time adjusting should be 1/4 turn clockwise; proper adjustment will almost always be right on or within 1/16 turn. you will likely have to readjust the CO mix to compensate.

__________________
Don't ask me, I'm a shop-owner by default

Here's a thread of what I went through making these adjustments. Lots of good links within.

Best of luck,

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Norm in NJ
Next oil change at 230,000miles

Thanks For The Info. I Found The Problem On Sunday. The Fuse In The Ovp Was Blown. I Check This After Looking Thru The Archives For A Couple Hours. Hope Everyone Has A Great Holiday Season!

Probably time to replace the OVP as well....

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I'm wondering why a blown OVP fuse would cause a hard start in cold weather, but not in warm weather?

No electronics would give you fixed mixture, hence no cold start valve or cold enrichment. The result would be difficult cold starts and stumble while warming up. Otherwise, will run fine.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!