Starting Issues - Need Ideas

J

jtownley

Member
I need some ideas on an issue that I am having getting my Scout started.

Details:

I have a 71 800B with a 304 and the Holley projection kit installed. Recently, I have been having issues getting the Scout to start. The Scout has a brand new red top optima, and it turns over just fine.

This weekend, I did a little troubleshooting on it. I pulled the fuel line off at the throttle body and then turned the key. No fuel being pumped at all.

I unplugged the plug at the fuel pump and checked the voltage during cranking and it is only 10.8 volts.

I then took a jumper wire from the battery to the fuel pump, and the pump appears to work (I.e. I can hear it pumping).

The weird thing is that once I jumped the pump from the battery and let it spin for about 10 seconds, I remove the jumper wire and plug the pump back in and then the Scout starts just fine.

If I let the Scout sit for an hour, it won't start again. I then go through the jumper exercise again and then it starts fine.

So my initial thought is that the pump is gummed up internally, and 10.8 volts is not enough to get it spinning. When I jump it from the battery with the full 12 volts, it spins fine (enough to loosen up the gummy stuff) and then it starts fine.

Is it time for a new pump?

Or, is there an issue with my voltage at the pump?

Thanks in advance for any ideas on this.
 
Sounds like the pump is draining the fuel back when the engine is off.
The GM systems run the pump when you turn the key on to prime it.
Could be the heat in the line builds when shut off and forces it out.
The system(ECM and pump) should be running from a relay to provide full voltage.
If you are powering it from the Scout wiring then your just asking for problems.

It sounds like both your concerns May be contributing to the problem.

You can use the same pump listed for the GM systems.
The universal has 3/8 in and out.

You could have a crack in a hoses causing it to draw air also.
 
I think you May have already answered your own question when you discovered less than 12 volts at the pump.

Solve that problem and you will most likely solve the rest of the problems as well.
 
Thanks bill.

I will say that it was a pain in the butt figuring out which terminal on the relay does what. The little picture they stamp into the side didn't really correspond with the layout of the pins. I had to play around with it and a battery to figure out what went where. In the end, it works perfectly.
 
Relays can be confusing.
Keep in mind that 85/86 can be swapped and 30/87.
If there is an 87 and an 87a then it makes a difference.
 
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