fuel pump system 2001 San gt40

[mjstonework122]

The boat is 2001 San with the gt40. It starts then idle will bounce up and down then stall. I pulled codes to see what might be stored and 87 comes up and also 96.
On this engine are there any likely suspects that I should test out. how do I know if it's the low, or high pressure side.

[Jonny Quest]

You may get some good responses on the “other” site…
www.CorrectCraftFan.com

[JayG80]

The boat is 2001 San with the gt40. It starts then idle will bounce up and down then stall. I pulled codes to see what might be stored and 87 comes up and also 96.
On this engine are there any likely suspects that I should test out. how do I know if it's the low, or high pressure side.

From the Manual in my Equus 3145 Manual:

87 Cars only Test Condition O,R,C..... Fuel pump primary circuit fault
87 Trucks only Test Condition O..... Primary Fuel pump circuit failure
96 Test Condition O,C....shows Fuel Pump Secondary circuit fault / high speed fuel pump relay open

O= Key Off, Engine Off
R=Key Off Engine Running
C=Continuous Memory

You can try:
swapping the ECM & Fuel Relays https://skidim.com/fuel-relay-12v-4rd.html
See if high fuel pressure is 39psi with Key On Engine Off. Test oat schader on top of FCC

[JayG80]

Until someone smarter comes along, make sure the wires are secure at the low pressure fuel pump. This was an issue on a recent thread.

Also, inspect the wires coming out of the top of your FCC, these are known to leak gas around the wires through the epoxy sealant. There is a brass retrofit repair kit that is recommended. https://skidim.com/kit-fcc-pass-thru-retrofit.html

See this thread https://www.planetnautique.com/vb5/f...ng-please-help

[mjstonework122]

Ok, so, I connected a fuel pressure gauge to the rail and got almost nothing when key on.
still very low while cranking. but once running I have almost 40 psi. could this be a clue? what pressure should i have with the key on position engine not running.

[gun-driver]

39 +/- 3psi
When you turn the key on you should hear your pumps turn on/prime the rail for about 2-3 seconds

[phillik]

Pressure seems fine. I wonder if the low pump just isn't keeping up (mechanical or electrical) with demand and starving out the high pressure pump.

The low pressure is more of a primer for the high pressure pump. It feeds the canister. The low pressure pump is easy to take apart and inspect for free movement. Had a friend, working on his GT-40, loose a washer in the pump in reassembly that caused a jam and somewhat the same issue. If you take it apart and its all fouled up you can just replace or try to clean it. We bench tested the pump to verify it was working. But as Gun-driver said, you should hear that pump run every time you turn the key on.

The high pump is somewhat of a pain to reassemble due to the filter gasket staying in place when slipping over the input side of the pump. Its easy to take apart with a oil filter wrench and check the bottom of the housing and filter for junk. Just make sure to disconnect the battery and de-pressurize the fuel rail so it doesn't spray all over when you start loosing things up. You can use a fuel pressure gauge and press the purge button to release the extra fuel if it has that feature.

These are some general fuel delivery checks and cleaning. If everything looks good, I'd start checking things with an ohm meter.