1995 gt 40 no fuel pressure at fuel rail.

[neo297]

My boss has a 1995 19.6 ' ski nautique with a gt 40 mpi not tbi engine. My understanding is that it has a 2 stage fuel pump( only 1) and no FCC. He asked me to look at it for him as it would not start. I do have mechanical experience working on motorcycles ,cars (my Alfa Romeo spider) and feel comfortable in an engine bay trouble shooting. I first noticed he had no alternator belt and could not find one under or around the engine??? I cleaned his spark arrestor as it was filthy and could get the engine to fire with starter fluid or carb cleaner sprayed into the intake but as expected it would not stay running. At least I knew I had spark. There was no fuel at the schrader valve on the fuel rail. I kneed to know first, does the fuel pump / ecm relay get any signal from the alternator before "turning on", Second where on the engine is the relay located on line I can find schematic but no pics of where it actually is. Third is there any physical check valve that could be clogged or stuck? He wants me to just order all new everything and I just do not feel that's the best way to sort this out. Lastly can I put 12 volts to the fuel pump to see if it pumps fuel to the fuel rail? Any help would be greatly appreciated.

[DanielC]

GT-40 fuel pressure check
http://www.planetnautique.com/vb3/sh...=fuel+pressure
GT-40 relay connections
http://www.planetnautique.com/vb3/sh...=fuel+pressure

You can also download the GT-40 service manual from this site.

Jumping pin 30 to pin 87 on the fuel pump relay socket will make the fuel pumps run. But if you ground the connection in the fuel pressure check thread I posted, you can check the computer being able to control the fuel pumps, and all the associated wiring.

[s_kelley2000]

I am reposting this from another thread but this may apply as well. You should also check the safety lanyard and switch by the throttle. The terminals on the back of that switch have been known to be pretty bad and can cause loose connections. Also the plastic on the lanyard itself can get weak from sun exposure and no longer hold the button in all the way. Both of those issues could be intermittent. If there is any play between the lanyard and the button try to stick a coin or something in there to tighten it up and/or get a new one from Nautiqueparts.com. If the lanyard is not on or a loose connection makes it seem like it is not on then the motor will crank all day but the fuel pumps will not power up. The week plastic on the lanyard stumped me for a good two hours at the dock last year.

[DanielC]

On a GT-40, the engine will run without the lanyard, as long as the key is in the crank position.
The crank signal overrides the "no lanyard signal"

[s_kelley2000]

Thanks Dan, I forgot it differed from the GM engines in that respect. You can ignore my post Neo.

[neo297]

Awsome guys thanks this gives me a good place to start

[neo297]

Just wanted to say thank you again. It was the relay that was bad. The reason I did not see them( the relays) when initialy checking things was that they had fallen off the metal tabs that are screwed to the plate where they are seen in the photos linked to above. I know what a relay is and looks like but just did not see any at first glance around the motor. They were dangling on the wiring harness down behind the engine possibly low enough to have been under water, I have seen water around the base of the engine before when the boat has been up out of the water when questioned my boss said he just turns on the bilge and it drains, and clearly they were just bouncing around. As soon as the new alt. belt and relay were in it started right up first turn of they key! Since there were two relays and I only replaced one and can not tell you which it was left or right as it was originaly mounted since they were both off the mounting plate I am assuming it was the fuel pump relay. With key on you now hear the fuel pump come on and prime the system.Thanks again
Paul

[DanielC]

Here is a thread about the two cube relays on a GT-40.
Post #10 has the color of wires going to each relay. That is the only way to identify the function of the relays, because the relays are identical.
http://www.planetnautique.com/vb3/sh...ghlight=Relays