OK I think I found the fuel pump relay. I unplugged it, and plugged it back in and the car happened to start. Once it started, I unplugged it, and the car died. I plugged it back in and turned the car over a couple times and it started back up. It is a yellow bottomed relay with a white plug.




I drove the car about 1/4 mile, parked it and just let it idle. About 10 minutes later, it died. I tried to start the car again but I could hear and feel that relay working when I turned the key, to engage the starter, and felt and heard it click back when I disengaged the starter and the car failed to start.

The car will not start presently. Would I be correct in assuming that my problem is probably NOT the Fuel Pump relay, or should I plumb in a fuel pressure gauge and check fuel pressure when I crank the car over to be sure?

I know the metallic rectangle in the picture below is the resistor pack for the injectors (my car is an 86) Are either of those two relays toward the top of the picture the injector relays? Should I look at those next?



Thanks,

 

This sounds like the trouble I had with my 93 suburban early this summer. It would just die at random times then later start and run.
Turned out to be the ignition control module. Check by replacement.
I checked prices on these and they arent cheap.

 

I don't think that is it because keying the starter is working the fuel pump relay everytime, if the car starts or not.

Could I be wrong here?

 

the silver box is the injector relay. and also, even though you can hear the relay under the dash click, that does not necessarily mean that i is working properly. but anyhow, change the injector relay, this could help out a great deal. and also about the fuel pressure, if you have a new pump, then you have pressure unless you have a hose leaking significantly. could also be the mass air flow sensor. or the actual ecu. whatever it is, its an electrical problem guaranteed! but i would start with the fuel system electrical......injector relay, fuel pump relay, main relay, or possibly the mass air flow meter. at least one of these if not all will fix your problem. also, adjust the tps all the way so that you cant see the bottom of the bolt. this will fix the tps if it is messing up on you.

 

Just an idea, check the fuel filter at the base of the fuel pump. You might have crud in you tank which clogs the filter temporarily, had missing while driving, it would stop hesitating if I parked the car for 10 mins and drove off.
I got the tank removed and cleaned out, put a new filter on the fuel pump base, so far no more hesitation. That filter is called the low pressure fuel filter, is not mentioned in the Haynes book, it should be, but it can be seen on a schematic of the pump. 12 bucks from the Mazda dealer, so use a new one. FWIW, Also referred to as the sock and a major cause of fuel starvation when gummed up.
Mike

 

I thought the silver box was the injector resistors not a relay? I can pick a new one up off ebay to try. This was going to be my next step.

I already changed the main relay.

I will try jumping the fuel pressure relay to verify functionality. I can see a voltage change in the volt gauge when the relay is energized, so I am inclined to think the fuel pump is working.

The TPS is adjusted properly, and that was verified with the RTEK.

I have an RTEK modified ECU. It should have been fully checked before it left their facility, and has been working fine for months. I am going to assume for the time being that it is NOT the ECU.

I thought about the air flow meter as well - this is definately a possibility.

 

When this problem started, I changed the fuel pump first.

The fuel pump is brand new, and the tank is perfectly clean. I had to reuse the old fuel sock as the one that came with my pump was incorrect. I thorughly flushed my old sock multiple times. It was not clogged to to begin with.


Thanks very much for all the help.. Please keep the ideas coming. I think I will be changing the injector resistor pack next.

 

Ok, I changed the fuel injector resistor pack, and it does the same thing. No change.

Tomorrow I am going to jump the fuel pump relay and see if that helps. I will also try to start the car with some starting fluid when it is not running. My friend will be here so we can see if there is spark as well..

Any other ideas guys? This is a PITA!

 

Update - PROBLEM SOLVED!

It ended up being the rear pickup in the CAS (Crank Angle Sensor). It would get hot and stop working, and there was no continuity across the rear pickup when checking the sensor per the FSM. We checked to see if there was spark, and there was only one spark when we first turned the key, then no spark after that. There did not seem to be fuel either.

If we sprayed the CAS pickup with contact cleaner, it would start working again, and there was continuity when checked per the FSM. The car could then start and run for a few minutes. After spraying the pickup, the car would spark normally, and there seems to be fuel delivery from the injectors.

I used a 2 LED diagnostic light in the test connector to find the problem. Interestingly enough, the code was only thrown when the car was cranking, so I did not see the code before. I had a friend with me today and was able to see the code. When the car was in the ON position, there were no codes.

Thanks for the help everyone.