Please Help!!! Engine Dies When Hot. (Problem Solved)
 

Hi All:

I just picked up a really clean 87 260E to replace my 260E with a blown tranny.

Today while driving it, the temp got somewhere between 80-100 and the car just ran rough for about two seconds and then died. It cooled off for about 5 minutes and started up like nothing was wrong. It ran for a few minutes, temp got hot again then died again. Same thing waited 5 minutes and it started up fine.

Am I running into a vaporlock situation? I am not sure. I got stalled 7 times trying to get home. After I tried to run the heater to keep the engine cooler but it still cut out after about three minutes. It was quicker to cool off when the heater was running.

I am at a total lost for what my be wrong. This car is too nice to just pull out the tranny and put it into my car right now. If it will cost too much to fix, that is what I have to do. Tranny R&R will cost $500.

Looking deeper into the situation, it looks like the previous did have A/C work done just before I got the car. The receipt shows he recharged the A/C last week because it went in because of hot air coming out of the outside vents. I don't know if this has anything to do with this situation.

Any help will be greatly appreciated.

Aloha,
Eric

So you still have the old car and you can try swapping some parts over. I would start with the fuel pump relay.

It would be helpful if you give more information about the rough running, is there a strong smell of petrol from the exhaust when this happens, does it idle rough but pull more smoothly, etc

Hi Mike:

Thanks for the reply. The car is currently on the other side of the island. I need to tow it home.

As far as the rough idle, when idleing in traffic, it goes towards 100 then it shakes the car for about two seconds then dies. I try to step on the gas but it just acts like no fuel is going in and struggles to rev then cuts out. The RPM's don't even go up when the gas is stepped at that point. It trys to rev but it just doesn't.

The car runs really strong up until that point. It has not cut out while driving at highway speeds yet. I am really thankful for that.

It smells like it is running a little rich at idle when the car is cold but I don't smell any gas coming from the exhaust after or just before it dies. I pulled the plugs and they look really good. Nice and brown and dry.

If it is the fuel relay, is there a way to bypass the relay?

Thanks again for your reply.

Aloha,
Eric

Sounds like the fuel pressure relay. Switch the one from the other car and repair the problem relay by resoldering cracked solder at pins on the circuit board. Cracks are expanding when hot.

I had a similar problem. Found that cleaning the distributor cap and rotor button contacts fixed it temporarily, new cap, rotor, leads and spark plugs fixed it forever. (I tried the fuel pump relay first but it had no effect)

crankshaft positioning sensor
 

I had the same problem and had to take my car to the dealership.
They spent many hours isolating the crankshaft positioning sensor failing after it would get hot. Hop this helps as it cost me over 800 to find solution.

Hi Earl, Andrew and Ed:

Thank you for taking the time to respond. That leaves me a starting point to work from. Once I tow my car with the broken tranny home, I will start swapping parts. The simplest first which seems to be the fuel pump relay and work from there.

I really appreciate all of your help.

Aloha,
Eric

Update
 

Hi All:

When the engine died tonight while driving, I pulled the fuel pump relay and jumped pin 15 and 87. The car started but idled very rough. Does this mean the relay is bad? I am not sure about the rough idle part.

Can anyone with experience with this chime in.

Thanks for all your help.

Aloha,
Eric

Not The Relay
 

Hi All:

Here is the latest. I swapped out the OVP and the Fuel Pump Relay with working ones and I still stalled out when it got hot. I placed the OVP and Fuel Pump Relay from the stalling car and put it into the donor car and it ran fine. Count that out.

I then did a full tune up changing cap, rotor, wires and plugs along with the coil because during the episode, I pulled the number one plug wire attached a spare sparkplug and held it against the manifold and got no spark. I let the car cool off and tried it again and the car started along with a nice spark.

Now comes the big question, what else have I missed. I am now sure it is not fuel delivery.

Would the flywheel sensor be the cause of this? If anyone knows of anything I may have missed, please let me know.

Thank you all for your help.

Aloha,
Eric

Could be the ignition coil. They can work fine when cold and malfunction when hot.

I agree with Neil - ignition coil. If the car purrs nicely when cold and stops running when hot - and there is no spark to plugs - the coil is very suspect.
Morris

Hi Neal and Morris:

Thanks for the replies I did replace the coil at the same time as the tune up. I suppose a coil out of the box could be bad. I will try to put in on my other car and test it later today. I will update you later about this.

Thanks again for your help.

Aloha,
Eric

Problem Solved
 

Hi All:

Thank you for everyone that has kindly taken time to respond. A big Thank You goes to Benzmac who helped diagnose the problem as a two fold problem.

Problem ended up spark stopped first then fuel delivery stopped immediately after. Solution ended up changing the crank refrence sensor then the fuel pump.

Today I am a very happy camper driving my new ride around town.

Once again Thank You to everyone!

Aloha,
Eric