Fuel delivery problem

[clough]

Hi guys, I have a 1977, 75HP Johnson Stinger on a 15' trihull that I'm trying to get up to snuff. It has run recently (3 wks ago) but it did had a some problems then (i.e., hard to start, once started, it idled great, but was completley sluggish out of the hole - felt like a cylinder was out and it never was able to reach WOT. Overheating was not a problem. Then it suddenly just quit, and of course a really nice pontooner was nearby for a tow (thanks again Josh). Now it won't start altogether. Heres the thing (and please don't admonish me for using starting fluid, I was desparate and rarely have done this because I know the deal!)...Anyway, with a little starting fluid into the carbs, it runs great (done twice on muffs), but then dies as if starved. I did find leaky gas lines, and replaced them all. However, this did not fix the problem. Now, to check the fuel pump, I had my wife crank the starter and motor while I looked at the lines (the lines to the three carbs are clear so that I can see fuel flow). There was no fuel -zero- going through the lines. So, my question is whether it may be a fuel pump gone bad, or if a cylinder has gone out and the pressure / vacumn cycle that runs the fuel pump may not be working any longer. My manual says the fuel pump can not be repaired but only replaced. Any thoughts? Thanks, Rich

 

[JB]

Re: Fuel delivery problem

What happens if you pump the primer bulb, Rich?<br /><br />If that moves fuel then your fuel pump may have failed, if not look to the fuel supply to the fuel pump.<br /><br />Good luck.

 

[clough]

Re: Fuel delivery problem

Yeah, pumping the bulb does get fuel to the pump (took the inlet line off to make sure). But from there to the engine, no fuel moves. I took the carbs off last night and cleaned them up - all passages are open. So, i'm pretty sure the pump failed. Looking for a replacement.

 

[BoatBuoy]

Re: Fuel delivery problem

You might want to do a compression check if in doubt about a cylinder.

 

[clough]

Re: Fuel delivery problem

Reposted with past posts included. Morning, I am still having a major problem with my 75 HP, 77Johnson Stinger. After a new fuel pump, new gas lines, cleaned carbs...I still get no fuel through the fuel pump (its not the tank or lines here either). It seems like there is no vacum (pulse?) from the engine to pull the fuel into the pump. Can someone give me the skinny on the theory of operation of this system and tell me what they think could be the problem. Again, as I posted earlier, it runs good when I spray fuel into the carbs. I have not done a compression test yet, that's next. I'm begining to believe the adage - Owning a boat is like standing in the shower tearing up $50 dollar bills. Rich

 

[Dhadley]

Re: Fuel delivery problem

Pumping the bulb should put fuel right thru the pump into the carbs. Does it?

 

[clough]

Re: Fuel delivery problem

No it dosen't, not with the brand new fuel pump, nor with the previous one that I thought was bad - but may not be. When I push in the ball gasket on the fuel line from the tank, fuel does flow through the gas tank line. Plus, when I spray carb cleaner into the high speed intake tube (in carb), it appears to be open into the throat. If fuel is supposed to flow all the way from the bulb into the carb bowl it doesn't. So there must be a plug somewhere, but I don't think its in the carb because when I spray carb cleaner into the bowel inlet tube port, it is sprays into the bowl. So, this mean that you think its probably not a crank-case vacum problem since the bulb will not fill up the carb bowls? (this would be good news!) this is begining to sound like a simple fix, that is hard to find. thanks.

 

[Dhadley]

Re: Fuel delivery problem

Your pump should have 3 hoses. Fuel in (from the tank), fuel out (to the carbs) and a pulse line.<br /><br />Where is the "fuel in" line connected on the pump?

 

[clough]

Re: Fuel delivery problem

I'll have to recheck it when I get home tonight - I'm pretty sure I hooked it the way the old one came off...but, if its backwards...yippie...and then you will be getting to know me! thanks for your help, Rich

 

[Dhadley]

Re: Fuel delivery problem

Well, lets hope its just that simple but it might not be. We just need to start with the basics.

 

[ob]

Re: Fuel delivery problem

You didn't mention it in your above post but there shouild also be a fuel filter before the pump.Is it clean and clear?

 

[clough]

Re: Fuel delivery problem

It is clean and clear - its new with the new pump. I have the line from the filter housing port going to the middle carb, the line from the tank coupling is going to the next port back towards the engine, and the pulse tube is on the port closest to the engine. (from memory).

 

[Dhadley]

Re: Fuel delivery problem

Oops!<br /><br />Lets start with one hose at a time. The tank line goes to the removable cap on the pump.<br /><br />It helps, but isnt an absolute, if the gasket that looks like a wheel with spokes is lined up so that a spoke is not covering the hole in the pump housing.

 

[clough]

Re: Fuel delivery problem

Oh man, I am so psyched, I did have it backasswards. However, i have not hooked up the gas tank yet because I am going to do a compression test first. I hope it dosent revert back to the original problem after all this. Cheers you guys, this site is incredible - now, I wish there was one for Jeep. Rich

 

[Dhadley]

Re: Fuel delivery problem

Your original problem may have been the old pump was tired. <br /><br />Just make sure you have the other 2 hoses correct. The middle fitting is "fuel out". It should feed the carbs. That leaves just the one fitting and as you said "closest to the block is the pulse line". <br /><br />Lets keep our fingers crossed.