Intermittant no start

[Joe 1320]

I get a random no start condition. There doesn't seem to be any repeatable pattern. Cold or hot, the starter will engage, but no fuel pump prime. I can put in the key, turn to run and sometimes the pump activates and sometimes it won't. I'm not talking about once the rail is primed, this can be a cold start after it sits overnight. Removing the key, waiting a few seconds and trying again usually activates the pump and the car fires right up. It's a fairly new 255 lph pump and casper's hot wire kit. If the pump primes and the car starts, it never cuts out or stalls from the pump cutting out. It flat out hauls and is reliable except for the starting issue. I've replaced the ignition switch thinking that the original might finally be giving up, I've even turned the alarm off and on to no avail. Oil pressure is fine, fuel level is fine, and like I said..... when it runs it never acts up.


Anyone have any ideas of where to look?

 

[85begalttype]

fuel pump is turned on by two things, the Fuel pump relay, and also the oil pressure switch. seems to me your fuel pump relay is acting up and should be replaced. The oil pressure switch powers the fuel pump if it detects over 2psi oil pressure. That is why it keeps running once its started.

 

[Joe 1320]

Hmm..... already replaced the relay when I did the new pump. Possible it's going bad, I'll check it out.

 

[BuickMike]

Hmm..... already replaced the relay when I did the new pump. Possible it's going bad, I'll check it out.

Where did you get the relay from? I had the exact same issue. It was the fuel pump relay on the pasenger fender. Here's the thing. There is another relay right next to it that looks identical, except for the relays have a divider in a different position so you can't mix them up. Not sure why since they are identical inside. Anyway, I bought a new fuel pump relay from Autozone and had the same problem. Later on I realized that they have their part numbers wrong and I actually replaced my fan relay. Here's how to figure it out. Disconnect your ECM power plug at the battery. Put one hand on the 2 relays and connect the plug with the other (make sure the ignition is on). Feel which one clicks. If it is the new one, move on, or replace it under warranty just to be safe. If it is the old one, then you replaced the wrong relay. I still had the old fan relay, so I just popped the divider out of it and plugged it in to replace my old fuel pump relay and have been problem free ever since. Hope this helps.

 

[Joe 1320]

Thanks Mike, I'll have to check that too. Interesting development, yesterday when it wouldn't prime no matter what, I took out a rubber mallet and tapped the tank a couple of times. Turned the key and it fired right up.