Switching from Volvo TBI to Carb on a 1996 5.7 GI

[camboat]

I have recently bought a 1996 2460 pursuit with a Volvo penta 5.7 GI with TBI.

The engine only has 80 hours on a rebuild. The problem that I am having is low fuel pressure and the wiring harness is bad.

I have replaced the tank fuel tube, check valve, fuel line, both fuel filters, both fuel pumps, and had the TBI rebuilt. I'm still not getting 30lbs of fuel pressure on the high side.

The wiring harness is obsolete and can't be found anywhere. I'm sure the VST is in the same shape.

So my next step is replace the TBI with a marine carb, low pressure fuel pump, and manifold. I'm not sure if I need a new distributor. Please let me know if I need anything else.

This will get rid of all the old parts so I can have it repaired anywhere if needed.

Attached is a photo of the distributor. Not sure if this will work with the conversion.

I will have a marine mechanic do the work.

Any help would be appreciated.

Thanks!

 

[Scott Danforth]

the TBI unit IS ONLY 30 lbs. if it was in a car it would be 15psi

what pressure were you looking for?

 

[camboat]

30 psi. I’m only getting 6-8 on the high side

With the bad wiring harness it’s going to be hard to troubleshoot.

 

[Scott Danforth]

the low pressure isnt a wiring issue. your regulator in the top of the TBI unit has debris, or your high pressure pump isnt running.

 

[camboat]

The TBI was just rebuilt. Both pumps are working. I have a strong feeling the VST has problems. So everything is new except the VST. Not sure if I can work on it.
Thanks

 

[alldodge]

Welcome
Found what I believe is you motor with HP pump on top the VST.

As Scott mentioned, it has to be the Reg or the pump with only 6-8 psi. My first thought is you have 2 LP pumps instead of 1 LP and 1 HP.

The tank only holds fuel and any fuel above what is needed by the TBI is returned to the tank. Your getting fuel pressure and it's not over flowing so it has fuel in it.

 

[camboat]

Thanks
When it quits raining here in the PNW. I will do more troubleshooting.

 

[Bt Doctur]

dist should swap with no issues ,I have a2 barrel vortec manifold that was on a 5.7

 

[camboat]

Here are a couple of pictures of the STBD side ecm plug. I ended up putting heat shrink on all the bare wires. The wires seem brittle. I don’t trust it to be reliable. If I could find a used replacement plug I could splice it in.

I can find a 5.7 GL wiring harness. Would that work if I swapped over to a carburetor? It sure would clean up my wiring mess and solve my discontinued parts problem.

 

[Scott Danforth]

was the boat sunk?

the connector is available from either LADD or TE connect. you need new terminals too.

regarding a carb, simply make your own wiring harness. its like $30 worth of materials.

 

[camboat]

That’s the only spot with the brittle wires.

Thanks for the info.

 

[Lou C]

I’d think about taking the time to replace the brittle wires of you can. Because if you can get it to work you could potentially save a lot of money. If not then see if you can find a harness for the GL model & if not you might be able to make one from the schematic.

 

[Scott Danforth]

The green is corrosion

The brittleness is from overheating