Needing help finding why I can't get fuel pressure.

Feb 6, 2019
72
None None None
I just installed a new engine in to a Catalina that has been sitting for... probably a long time. It has been working fine on a gas can but now that I connected it to the tank it won't start and the fuel won't prime.

Here are all the clues..

The electric fuel pump can't get fuel pressure. You hear it working but the fuel filter located before the pump stays dry.

I couldn't blow air to the fuel tank when I took the line off.

When I connect the pump to a gas can it primes and engine starts... works no problem.

When I pour fuel down in to the tank filler hole, it goes down very slowly.

I took the fuel cap off and tried to blow air or get pressure and it didn't help.

Any ideas here? Is there a fuel shut off valve? I can't find anything like that.

This is a 78' Catalina 30.
 
Feb 6, 2019
72
None None None
Hmm how do I get access to the pick up line in a Catalina 30?

It looks like the fuel line runs forward from the aft of the boat.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
Find the fuel tank, the fitting will be on top of the tank and then remove the pickup and and the screen. Try to siphon some gas from the bottom of the tank and look for debris and water.

If the prior owner put E10 or E15 gas into the tank, the tank will need to be drained and cleaned and all the fuel hoses replaced.
 
Nov 6, 2006
9,885
Hunter 34 Mandeville Louisiana
If the tank fills very slowly, you probably have a plugged vent line on the tank.. most likely at the vent line thru-hull. In addition, most likely a small air leak in the line between the tank and the pump. could be something like the packing in the shutoff valve, but if the line is old, it may be cracked and leaking air into itself when the pump is working. Air leak may be at one of the fittings between the pump and the tank.. could be a bad fuel filter seal.. Not easy to find sometimes
 
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
There should be a fuel shut off valve at the tank. It prevents siphoning if a hose leaks below tank level amongst other things. Fill the filter with fuel to help the pump prime.
 

ToddS

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Sep 11, 2017
248
Beneteau 373 Cape Cod
If you can't blow back through the line to the tank... it is unlikely that a small air leak is your problem. Something is definitely either shut off, or blocked... follow that fuel line along its way and look for any connections/filters/screens/etc. until you find the one that is stopping flow.
 
Feb 6, 2019
72
None None None
Thanks for the tips! I'll go looking for the tank today. I'm hoping it's somewhere accessible with an inspection port.

I'm guessing it may be under the quarter berth..
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Gas or diesel engine? Same issues though: vent or pickup tube.

They also made 6,200 or so of these boats. Find the boat manual online.
 
Jan 19, 2010
1,169
Catalina 34 Casco Bay
Mud daubers is a great clue.. Check the tank breather vent. Mud wasps start building a nest before realizing that it's too small. Lack of a vent creates a vacuum.... Nature abhors a vacuum.... AND SO DO DIESELS and gas engines
 
Feb 6, 2019
72
None None None
Few more clues..

The fuel supply valve was open. I closed it before removing the line.

I can blow air down the fuel supply line.. so it's not clogged.

The fuel supply fitting has a slow drip with the valve open. 1 drop a sec.

The fuel vent line sprayed gas as soon as I removed the line. Fuel is pouring down the line and up out of the tank.

I have no fuel gague anywhere so I assumed that it was empty at first. But obviously it's overfilled. Turns out the fuel gague is on the tank!

So here's the mystery... if the fuel vent is spraying gasoline... why isn't the fuel line? Looks like the problem is in the tank suply fitting/valve?
 

Attachments

Jan 7, 2011
4,727
Oday 322 East Chicago, IN
You do have a fuel gauge. It is that round thing on top of the tank.

It I can’t read it in the photo.

If the fuel vent line ( the black hose in the corner with 2 hose clamps) sprays fuel, then there is a pressure buildup in the tank and the vent is probably blocked. The vent should allow the tank to “breathe”.

The fuel pickup tube is under the fitting with the shut off valve. I can’t see how that fitting comes off the tank, but you need to remove it, and the pickup tube should be connected and runs down into the tank. Check for a screen at the bottom of the tube, or check the inside of the tube for blockage.

Greg
 
Feb 6, 2019
72
None None None
You do have a fuel gauge. It is that round thing on top of the tank.
Yup I mentioned I found it on the tank above

If the fuel vent line ( the black hose in the corner with 2 hose clamps) sprays fuel, then there is a pressure buildup in the tank and the vent is probably blocked. The vent should allow the tank to “breathe”.
The pressure in the tank and the line could also be from excess fuel in the lines above the tank?

A good test would be to try and blow air out the vent line. That would indicate if it's blocked.. I wanted to try that but the fuel just gushes out in to the bilge. Nees to get that under control..

The fuel pickup tube is under the fitting with the shut off valve. I can’t see how that fitting comes off the tank, but you need to remove it, and the pickup tube should be connected and runs down into the tank. Check for a screen at the bottom of the tube, or check the inside of the tube for blockage.
Sounds like a good plan. Trying to be careful not to damage the aluminum..
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
Maybe it is over filled...is it gas or diesel?

But it wouldn’t create much pressure (head pressure maybe)...but it would flow out of an open line I guess. Get a bucket and drain some of the fuel out.

On the fuel gauge, I have one that looks like that...hard to get to also. Mine had a small connection (nut) that I could connect an electric fuel gauge to, along with power and a ground wire, to get a fuel gauge at my helm. You do need to know what ohm range the sender is set up for and then match the fuel gauge to that. Not sure if yours is the same, but it was an easy set up.

Good luck.

Greg
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
The fact that fuel sprayed out when you disconnected the hose means the vent is plugged.

This can prevent you from pulling fuel but not likely.

I would try disconnecting the fuel line at the carb and see if fuel flows

Fix the drip!!!
 
Feb 6, 2019
72
None None None
It's gasoline for an Atomic 4.

The fact that fuel sprayed out when you disconnected the hose means the vent is plugged.
Good ideas. I did more testing...

New clues..

I can blow out the vent hose. No blockage. (A)

I can blow air in to the gas tank through the supply port on the tank (B). No blockage there..

But I can hardly blow any air through the shut off valve (C).. in any position... or direction. strange.. headed to west marine to get mugged.
 

Attachments

Jan 27, 2008
3,045
ODay 35 Beaufort, NC
Take off the valve open it and see if you can see through it or run a piece of wire through it. You may not need a new valve if it’s just a piece of crud in it. Be extremely careful with “gasoline in the bilge” with the leaks you experienced you now have an explosion potential! Gas fumes are heavier than air and accumulate in the low point. Do not create and sparks, don’t use the stove or turn on switches until you empty the bilge and use a blower to remove any fumes! I saw a boat blow up once in a lake and burn to the waterline, crew in the water needing rescue. If you don’t understand this or are uncomfortable get professional help!