About to go insane about my 470!!

[foste1cc]

Hi. New here. Hoping you all can help me out! I have an 82' WellCraft 20V, with the infamous 3.7L 470 (S/N#6161927). Starts great (warm or cold), idles great at 700RPM once warmed up, butt bogs down at 2100 RPM. Carb's completely rebuilt and adjusted (including choke, rods, float, jets, etc..( Rochester 2bbl 2jet)), points are in good shape, adjusted to .022". Tank drained and filled with new gas (w/ some SeaFoam), New plugs, gapped at .035", new plug wires, Dwell set to 31°, Timing is at 8°BTDC, but I plan to adjust to 4°BTDC. Compression is at 112 +/-3psi across all 4 cylinders. Oil pressure good. Temp good. Plugs still look new after idling and cruising around under 2000RPM. A week ago when it wasn't even starting or idling, I realized I wasn't pumping fuel and bought a new fuel pump from Amazon for $39. That finally got me up and running, Looking back at that purchase, the reviews for that product were hit and miss :/

I feel like this HAS to be fuel related... Do you think the $40 fuel pump is just too cheap to work properly?

 

[Lou C]

Could be I'd try to get a Carter marine pump if you can find it.

 

[JonBoat55]

Have you looked at the anti-siphon check ball in the fuel line?

 

[Lou C]

Good point, I had to change that on my boat a long time ago.

 

[kenny nunez]

Pull the suction tube out of the tank and remove the fine mesh screen that is inside it then pitch it in the trash.

 

[Alterry]

Pull the suction tube out of the tank and remove the fine mesh screen that is inside it then pitch it in the trash.

Make sure the gasket thickness at fuel pump mounting surface is the same as what was removed. If you aren’t sure, use a mercruiser gasket, that should have the correct thickness. Best thing is to check the fuel pressure if you can

Also this could be mechanical advance related, clean that up if you haven’t done so in awhile, it’s just below the breaker points.

 

[Scott Danforth]

compression is seriously low at 112psi. could be from not running.

agreed, get a new carter pump. summitracing has them for the 470

 

[foste1cc]

Thanks for the replies. When I originally drained the gas tank, I did so by removing the main fuel line at the fuel pump, attached a coupler and a length of tubing running out of the boat into a bucket. I grabbed my compressor hose, blew into the gas fill-up with a rubber grommet and my air gun nozzle, and plugged the vent under it with my thumb.

REALLY hoping that makes sense... It blew out about 4 gallons in a consistent steady flow. I guess I was under the assumption earlier that I could rule out that check valve being I drained the tank the way I did. Maybe not though?? Thoughts?

 

[foste1cc]

compression is seriously low at 112psi. could be from not running.

agreed, get a new carter pump. summitracing has them for the 470

What should the proper compression be?

 

[foste1cc]

compression is seriously low at 112psi. could be from not running.

agreed, get a new carter pump. summitracing has them for the 470

Just looked at summitracing's website, when I put in "Carter Marine Fuel Pump" 4 results show up. I called and spoke with a tech, he couldn't dig up which one is for my engine. Do you know which of those 4 are for the 470?

 

[Dubed]

Just looked at summitracing's website, when I put in "Carter Marine Fuel Pump" 4 results show up. I called and spoke with a tech, he couldn't dig up which one is for my engine. Do you know which of those 4 are for the 470?

Hmmm... I bought mine from Summit about two years ago, so they have (had) it. I believe there are two types for the 470, one with the bowl on top, one with the bowl on the bottom. I have the one on the bottom. Maybe that will narrow it down

 

[Scott Danforth]

Just looked at summitracing's website, when I put in "Carter Marine Fuel Pump" 4 results show up. I called and spoke with a tech, he couldn't dig up which one is for my engine. Do you know which of those 4 are for the 470?

The one that says it fits the 3.7 liter

 

[foste1cc]

Before I tare out the panels and sealant to get to my gas tank/line/check valve, Can I bypass all of this temporarily and hook up an external 5g gas tank with primer bulb directly to my fuel pump?

 

[Scott Danforth]

primer bulb is not legal on I/O motors. but you can take the inlet fitting of the fuel pump and dump it in a 5-gallon tank.

 

[foste1cc]

Okay, got it. I'm also just thinking of buying fuel pressure tester. Unsure of how I'm going to tap into the hard fuel pipe from the pump to the carb..
Anyone know what psi I should be pumping??

 

[charliedaubitz1]

Okay, got it. I'm also just thinking of buying fuel pressure tester. Unsure of how I'm going to tap into the hard fuel pipe from the pump to the carb..
Anyone know what psi I should be pumping??

about 5-6 psi

 

[Scott Danforth]

mercruiser makes a fuel pressure test adapter.

you should see 3-6 psi

 

[ROY WILLIAMS]

Hi. New here. Hoping you all can help me out! I have an 82' WellCraft 20V, with the infamous 3.7L 470 (S/N#6161927). Starts great (warm or cold), idles great at 700RPM once warmed up, butt bogs down at 2100 RPM. Carb's completely rebuilt and adjusted (including choke, rods, float, jets, etc..( Rochester 2bbl 2jet)), points are in good shape, adjusted to .022". Tank drained and filled with new gas (w/ some SeaFoam), New plugs, gapped at .035", new plug wires, Dwell set to 31°, Timing is at 8°BTDC, but I plan to adjust to 4°BTDC. Compression is at 112 +/-3psi across all 4 cylinders. Oil pressure good. Temp good. Plugs still look new after idling and cruising around under 2000RPM. A week ago when it wasn't even starting or idling, I realized I wasn't pumping fuel and bought a new fuel pump from Amazon for $39. That finally got me up and running, Looking back at that purchase, the reviews for that product were hit and miss :/

I feel like this HAS to be fuel related... Do you think the $40 fuel pump is just too cheap to work properly?

MY MCM 470 YEAR 1978 the engine 46 year ago 2024 ...
The carb inspect .. the 93 octane gas ....
the engine oil sn plus 6 oz the engine oil 30wt ...5.5QT ...
my Wellcraft boat 20ft very good job !

foste 1 ---- the engine compression pressure 4cyl 130-150 psi ......so fuel gas pump ....3-6 psi ..

 

[Grub54891]

I've seen more than 1 where the weights/springs under the points were completely shot!

 

[Scott Danforth]

or the $5 bushing is shot.