No fuel on 120 (2.5l)

[acicomp]

Hey folks,
I have an '82 Mercruiser 120 (2.5L) Based on my previous posts, it had sat for a couple of years before I got it. I have not been able to get fuel to the carb at this point. I changed the mechanical fuel pump yesterday and all the fuel lines as well since they were old auto rated fuel lines. It does have a Sierra water separator in line as well. I have cranked it for a while and still no fuel up to the carb when I crack the line at the carb. I had thought about possible a vent line clogged, so I have pulled the gas cap and still no fuel. I can blow in the line to the tank and get bubbles and I can also draw gas out of the tank by siphoning on the hose as well. I have also tried using a small 2 gallon tank as well by dropping my tank hose in there as well.

After searching through forums and parts diagrams, I don't think this motor had a push rod for the fuel pump. It appears to ride on the cam. I also didn't see a rod in the opening. Supposedly, it worked fine the last time the previous owner had it.

I am going to grab a new filter for my separator today. Does anyone know if I might need to prime that filter first? The fuel line runs about 3-4 feet from the tank to the filter/separator and then another 5 feet to the pump. The filter size is a Sierra 18-7845.

Thanks for any help here!

 

[alldodge]

You don't have the in and out lines swapped?

If not I would pull the pump and check the pump arm. Then move it and see if you can draw a vacuum on the inlet side. Also being a new pump, open it up and make sure something is not missing or installed incorrectly inside

 

[Alumarine]

What he said.
Also get a portable fuel tank and run it directly to the in port on the fuel pump.
Then run a line from the out port to the carb bypassing the other filter.

Have you checked the fuel filter on the carb inlet?

 

[acicomp]

It's not getting fuel to the carb at all. I have pulled the line off the carb to eliminate the carb as an issue by being clogged up. I have also pulled the line off of the tank and put it in a separate gas can to see if it would pull the fuel out. I double checked the pump before installing it yesterday to make sure it was pulling some air and I can feel suction on the "in" side and feel air coming out the "out" side when I move the arm. I am going to bypass the separation filter this evening when it stops raining to see if that makes a difference. I am also going to pick up a new separation filter this afternoon. These same symptoms existed before I changed the pump and fuel lines, so I am narrowing it down to what pieces are still in place that haven't been checked or changed.

 

[alldodge]

Sounds like you have a water separator filter and the one that's part of the pump. If so did you fill the filter and also how high is the filter above the tank and pump

 

[acicomp]

The separator filter is mounted about a foot above the tank and has about 3-4 feet of hose between there and the tank. I haven't filled the filter yet. Ill try that this afternoon when the new filter arrives just in case it needs to be primed. Again, this thing is bone dry where it's just sit for the last two years.

 

[dannys2004glastron175mx]

I always fill the filter before spinning it on

 

[alldodge]

The low volume pump you have doesn't have a lot of suction and will have a hard time filling the filter. The height should be as low as possible to reduce the amount the pump has to lift the fuel.

This could also be the issue from the previous pump

 

[acicomp]

Well.. .I now have fuel, but I am pretty sure, after all the other gunk that was in the lines, that the carb needs to be rebuilt now. It definitely couldn't hurt. Won't stay running at this point at all. Seems to be starving.... I'll check the pressure, but I would say it needs cleaned out pretty bad.

 

[alldodge]

Boat's sure take time and more money. Sure looking forward when you get her running good for the season

 

[fishrdan]

I'm a bit late here, now that you have fuel to the carb, but when I need to prime the carb of my 140HP Mercruiser I remove the spark arrestor from the carb and dump a bit (tablespoon?) of fuel down the carb's throat, then start the engine. That's usually enough to spin the engine fast enough to push fuel up to the carb. If the fuel system is dry it may take a couple tries to get fuel all the way through the system, but it's better than cranking on the starter for several minutes. (Keep fuel container away from the engine/carb.)

I rebuilt my carb a couple months back due to the engine idling like carp. I used the "Pine-Sol" cleaning method and couldn't believe how clean the carb came out, squeaky clean. As an added bonus, it smells much better than that noxious Berryman Chemtool.

 

[acicomp]

I pulled the carb inlet filter last night and it looked great. It was one of the old stone style filters. I may add some fuel to the throat to fill the bowl first and also put a pressure gauge inline to double check pressure before I pull the carb and go through all of that. I'm fairly sure it could use a cleaning, but if not, this will let me know before I go through all that.

 

[acicomp]

Mercruiser 120 2.5l fuel pump blockoff plate? (electric conversion)

I'm working on my "no fuel" issues on my carb/pump and staring to think ahead, just in case. IF I happen to have a bad cam lob and need to switch over to electric, has anyone who has done this please let me know which block off plate you used in place of your mechanical fuel pump? Many of the parts auto parts stores carry the block off plate for a Chevy v8, but I wasn't sure if this would fit or not.

And yes, IF I choose to go this direction , I will be using a marine rated pump (Airtex E84389) and the oil pressure switch (Airtex OS75) to make sure it done properly. That pump is 5-7psi with the 3/8 line connections.

Thanks for nay help...

 

[Bondo]

Ayuh,.... There's no reason to go electric,.....

Mechanical pumps work just fine,....

I can blow in the line to the tank and get bubbles and I can also draw gas out of the tank by siphoning on the hose as well.

That's not right, there should be a one way check valve at the tank's outlet, per CG regulations,.....

Prefillin' the canister filter will help,...
Lowerin' the mountin' point might also help,....
When ya try to start it, dump a 1/4 once of gas down the throat of the carb, just before ya try it,....
It'll run til that gas is burnt up, 'n should allow the fuel pump to bring up fuel to the carb,....

 

[acicomp]

I can't speak for when the regulations went in to place for that one way valve, but that's how it's set up. (no check valve) I have the 90 degree barbed fitting that screws into another fitting that appears to be welded/pressed into the tank. I can see the pickup tube down in there, but no way to get to it. I can both siphon and blow bubbles. Maybe lack of experience here, but I haven't been able to figure out how in the world to pull the whole pickup tube out. It's like the 90 degree svrews into another fitting that screws in to the tank, but the filler tube seems to be part of the metal tank...?? I'll have to deal with the check valve issue after I get it running.

I was able to drop the filter down about 6 inches or so last night. I'll try the fuel in the throat tomorrow when I get back to it in order to make sure the bowl is full.

I also get and agree that mechanical pumps are the way to go... The question was based on a future possibility. IF the cam lobe was worn and not allowing enough movement of the pump and I HAD to switch to electric, has anyone done this on a 2.5l and if so, what blockoff plate did they use. My goal is to keep it a mechanical setup, if at all possible. Not trying to put the cart before the horse, but I would rather be able to lay out a game plan to get this thing running soon.

Thanks again

 

[Bondo]

but that's how it's set up. (no check valve) I have the 90 degree barbed fitting that screws into another fitting that appears to be

Ayuh,..... The babed fittin' is Supposed to be the anti-siphon valve,.....

Somebody changed it out,....

make sure the bowl is full.

The fuel pump fills the bowl, the splash of gas it to run the motor a few seconds, insteada grindin' away on the starter,....

and if so, what blockoff plate did they use.

Just leave the old pump bolted to the block,....

 

[alldodge]

The valve screws into the 90 degree tube, then the hose is connected to the valve. Many have removed them over time because they have trouble getting fuel. The valves have two functions, to keep the fuel tank from draining into the bilge if the fuel line brakes, and also keep the fuel line full of fuel. Without the valve the fuel pump has to suck the fuel up from the tank to the filter on every start up.

If valves are working correctly there great. They come in different sizes.

http://www.iboats.com/Moeller-Anti-...9080028--session_id.750960021--view_id.392106

 

[acicomp]

I can pick up a new valve over at a local marine shop not far from here. Does anyone have any experience with a tank like this? I can get some pics later on if needed.

 

[alldodge]

Here is my tank, it has 90 degree fittings welded to the tank. The valves are screwed into those fittings. If yours are different maybe a pic would help

 

[Bondo]

Ayuh,.... I've seen tanks where the dip-tube is part of the tank, non-removeable,...

Others, the dip-tube screws out with the 90? fittin',....

You can always sweat a 3/8" copper dip-tube to the tank side of the 90? fittin' too,...
I've hada make that repair before,....