Gt-40 starts but won't stay running

[jslow68]

I was out yesterday and the boat was running kind of rough. So I replaced the plugs and added some seafoam. It seemed fine, but the check engine light was flickering every now and then. As I was ideling in it just shut down and wouldn't start. Today I went to start it to see if I'm getting fuel up to the fuel rails and it is squiring out the valve. It will run for a couple second then shuts off. It also was backfiring? Could the timing be off?

[DanielC]

Do this:
http://www.planetnautique.com/vb3/sh...ressure-Check&
Do this:
http://www.planetnautique.com/vb3/sh...ignition-test&
Check the safety lanyard switch for bad connections.
Down load the GT-40 service manual from this site

[jslow68]

I pulled the fuel control cell open and it's dry as a bone. I cycled the engine with it off. I hear the low pressure pump cycle but it doesn't spit any gas. Anybody have an idea????

[horkn]

relays

[DanielC]

The relay does not move fuel.
The fuel pumps do.
I would suspect the low pressure fuel pump.

I do have one low pressure fuel pump sitting on a shelf that would not draw any fuel until it was primed. Then it pumps just fine.

There is gas in the tank? Are you sure?

[jslow68]

I replaced the relay and fuel filter a couple weeks ago. I was getting fuel in the FCC but not to the rail. Turned out it was a loose wire on the high pressure fuel pump. Now I'm having this trouble. Should I replace the low pressure feul pump?

[DanielC]

If you do this, you will be handling gasoline, in open containers, in your boat. Be very careful.

Review my post on checking the fuel pressure. That shows you how to turn the fuel pumps on.
There is a hose connected to the side of the FCC that is the return line back to the fuel tank. Disconnect that hose, put a can under the open fitting. When you turn the pumps on, you should get good flow, about a quart every 15 seconds. Plug this fitting with a fuel pressure gauge. You should get 5 to 6 PSI.
If you have good flow here, and good pressure with the fitting plugged, with the pressure gauge I would think your low pressure pump is good.
This is not the pressure you need at the fuel rail on the engine. that should be 39 PSI, fuel pumps on, engine not running.

[bobchris]

temp and oil switch would never cause this problem funny how it's alwys over looked as a cause for the computer shutting down the motor right after it's starts bet it went in to limp mode before you turned it off the first time too, but where under idle and didn't notice that it did.

[jslow68]

I checked the anti-siphon and was working fine. I sprayed it with a little brake cleaner just to be sure. I then replaced the low pressure fuel pump and it fired right up. So that was my problem.
Thanks for all the help.