This problem might be old news for some but bear with me as some might be just experiencing it.

My problem began several years ago with the rare incidences of stumbling start after sitting for 10-30 minutes in the summer heat, then lift the bonnet and let it sit for 30-45 minutes and it would start. Late last summer it began to intensify but there was no stumbling start; it just wouldn't attempt to start at all. When switched on the key light would not come on, therefore no fuel pump or injectors. Sometimes the key light and CEL would come on but as soon as start was initiated it wouldn't and the lights would go out until the wait was over.

This spring a new symptom showed up. With a cold engine in the morning the key and CEL lights wouldn't come on but if you would leave it switched on for a few minutes they would come on and there was a very audible clunk when the main relay pulled in and it would start. Having worked in electronics and electro-mechanical gear for 40 years this smacked of a resistive connection to me, but where was it?

As part of the back story, I attended a 2 week soldering school when in the USAF and had completed the course as a NASA certified solderer....sounds impressive huh? With that knowledge I figured I knew all I needed to know about solder joints so when I read on tech forums about cold solder joints on the main start relay possibly causing the problem I had taken the relay out back in the spring and inspected it with a jeweler's eye loupe and deemed that all the solder joints looked fine. Belligerence is an undesirable human trait except in the time of a fight, and I belligerently had decided that the relay wasn't the problem.....was I ever wrong.

Saturday morning I retraced my steps and with stacked magnifiers I found the evidence of cold joints, resoldered them and now have had three days and over 30 starts without a problem.

There has been a lot of speculation and conjecture about the problem being a "heat soak" and vapor locking problem, some swear by it, some say "no way can it vapor lock", higher pressure FPR's, ECU's, Odyssey rails installed, blah, blah, blah, a lot of expense, aggravation and consternation has been endured but the main relay could be the principle problem in most instances and I'll explain why.

There are actually two relays contained in the "Main Relay" case as well as a ceramic resistor which steps 12 volts down to 6 volts for one of the relays. Why they chose to use a 12V and a 6V is beyond me and maybe there is a good reason, but point is, the coils and resistor are the only heat generating parts of the mix and are most likely responsible for the heating/cooling contracting and expansion within the relay case which causes the cold solder joints to form, and has little or nothing to do with the heat soak/vapor lock theory.

Bottom line, resolder the relay coil and resistor pins where they're soldered to the board and see if that doesn't fix your problem. RT

 

Seeing "heat soak" issues in the spring/summer is NOT the norm. When winter blend gas comes out is when the issue will show up.

Glad you were able to sort out your issues and thanks for posting what worked for you.