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1992 Merc 3 litre dies after couple mins up on plane

R

rodders

New member
"Hi, This is an Impressive dis

"Hi, This is an Impressive discussion group. Hope you can give me some help with my problem? Bear with me as my description of problem may be a bit drawn out.I apologise in advance.

I have a 1992 Stingray 537zp with a 3 litre Merc.
Engine starts and idles/revs fine on the drive with muffs connected. Drop it in the water & motor out into the bay and open her up (3000 - 4000 revs)and climbs quickly on to the plane for about 2 minutes then dies on me. First time this happened i could not start her back up. Had to be towed back to slipway.Suspected Fuel as i have spark.
Removed filters at pump and carb and cleaned.Some gunk present but seemed lack of fuel at carb inlet. Replaced fuel pump over winter and winterised boat inc fuel stabiliser. This season Fired up on the drive with outdrive in tank of water ran fine. Dropped her in the water and motored out(speed limit)into the bay and opened up. She went beautifully for about a few minutes and then lost power on me again. But this time i throtttled back and she will run at 1000 revs 5-10 knots. but repeats the process again when i get up on the plane. Still suspect carb/fuel problem.
i have carb dismantled at home and looking at pump plunger inside. Manual says invert and catch Ball from under plunger. Mine did not have a ball.
It is a good 2 hour drive to my cruising grounds so Any suggestions / help would be most welcome & appreciated.
Regards
Rod F"
 
"Sounds like you have a fuel v

"Sounds like you have a fuel volume issue. Sounds like you've got enough fuel volume to the carb to sustain idle condition but when you get on it, you suck the fuel bowl dry.

Sounds like you have stopped up filters along the supply line.

Do you have fresh filters? Not sure, but some have a small filter right at the carb inlet that often gets overlooked."
 
There is one in the top of a m

There is one in the top of a mech. fuel pump. Also check the fuel tank vent line for a drooping segment that could contain fuel and prevent suction. That can be verified the next time it quits by loosening the fuel filler cap.
 
""check the fuel tank vent

""check the fuel tank vent line for a drooping segment" - Mine did exactly the same thing, time after time, until I discovered the tank vent hose was drooping. On full throttle fuel entered the line and after a couple of minutes the motor would slow and die. After I figured it out I realized that I had just filled the tank to the brim. Probably would not do it on a less that full tank. Bout drove me around the bend. Hope this is your problem cause it's an easy fix - just tie the vent hose up higher. JW in Dixie"
 
"Thanks for all the suggestion

"Thanks for all the suggestions Guys.I will certainly be looking at the vent hose issue. Though there was never a problem with this before start of last season and vent hose is well supported with no dips / kinks.
Can anybody expand on my question regarding the pump plunger inside carb? Should there be a ball/strainer at bottom of pump plunger return spring or does it depend on carb model? There appear to be two Mercarb carbs that are applicable to the 3 litre Merc.The model that ties up with my engine serial Number definitely shows components below the return spring that are missing on my carb.
Mistahays certainly confirms what i was thinking regarding lack of fuel volume at carb.Thats why i replaced Fuel pump. There was plenty of fuel in the float chamber when i got carb off but i had only been idling when last used, so not conclusive!
I was aware of the small filter at entrance to carb but have only removed and cleaned it.I'm thinking i should replace it.What psi pressure should i be getting to carb if i can rig up a gauge in line? I think i need to check pick up in tank as well if its possible to get at.
The Fuel pump is a brand new Carter pump from Partsman @ Lighthouse Marine in NY.Which was third of the price quoted here in UK even with import tax.
Please keep firing in any suggestions that i can try on the drive but as i said in my previous post, problems only show up under load and at high revs which means i have to tow the boat 140 mile round trip to dunk her in the sea to give it a fair trial. With petrol at $10 a gallon (your money) here in UK, It gets pricy.(Sorry Guys, not your problem, me just having a whinge)
I might have to seek professional help soon (and get someone to look at the boat too)If i can't sort it out here.
Really appreciate all your input.
Regards
Rod F"
 
"Rod;
Your fuel supply at the

"Rod;
Your fuel supply at the carb should not drop below about 4 psig. If that is maintained, you know the fuel supply is OK.

If in doubt I would change the inlet filter; and having a spare on hand for that little guy is a good idea. It is your filter of last resort, so to speak, but it plugs quickly if it see any crud.

No expert on that carb, but I agree that there should likely be a check ball under the accelerator pump plunger. Anyone else know for sure?

Rod"
 
"Rod Stewart
If this carb is

"Rod Stewart
If this carb is a 2bbl, as I recall the accelerator check valve ball is situated under the spray nozzle insert. It is held in place by a "T" piece of metal that holds a light spring over the ball. The top of the "T" sits flush with the top surface of the bowl and is crimped in by the bowl material. I can't seem to find it on any of the 2bbl pics right now.
Bert"
 
"Mr Farris,

Good for you fo

"Mr Farris,

Good for you for boating at $10/gal. I'm going to be paying up too with my new lady to the left.

I would not suspect your accelerator pump as being the issue as would show up as a stumble under tranient throttle conditions and not steady state. Sounds like your engine dies under load but in steady state as it sucks the fuel bowl dry.

A not-so-safe remedy would be to "bottle feed" it with a small tank plumbed directly to the carb to gravity feed fuel and see if the problem goes away (think of an IV bottle in the hospital - or the one with bourbon in it by my reading chair). If it runs well, you can work your way upstream till you find the problem.

That said, if you have a known good pump and clean filters (as it sounds like you do) you may have trash on the fuel pick up sock in the tank. Try and expose the top of the fuel tank surface. Frequenly there will be a circular panel with the fuel pickup, fuel guage sender and everything in a removable package. Just thoughts. DH"
 
"Thanks Rod,
I will follow yo

"Thanks Rod,
I will follow your advice regards filters.And try and check pressure if i can source a gauge and fittngs.

Hi Bert,
Sorry to sound blank but Do you mean the small valve that sits in the bottom centre of the float bowl and lines up with the spring loaded pin in the float cover?
The numbers 15396A-4 2702 are stamped on the side of the carb for ID, but i can't find a numbers match in spare parts section.
I have also found what looks like the correct Accelerator pump kit part no 1397-8880 - 77282 This is identical to mine.
( I have a confession to make as to why i am so interested in the ball check valve at bottom of the accelerator pump. Last season one of the first things i did was to take the carb off and remove the float cover to clean out the filter and float bowl which was very dirty.And i was wondering if i hadn't noticed this check ball had fallen out.I didn't have my manual with me then cos a friend had borrowed it so i wasn't prepared for it. I don't think this is the case but there i've come clean anyway. I Had the engine failure before anyway which is why i took the top off the carb in the first place.
Regards
Rod F"
 
Rod;
You should be able to ge

Rod;
You should be able to get a fuel pressure test gauge and fittings at any auto parts store. Pretty common stuff.

Rod
 
Bert;
Thanks for the clarific

Bert;
Thanks for the clarification on the accelerator check ball. I am not conversant with the 2 bbl Merc carbs at all.

Rod
 
"Hello Mistahays,
Congratulat

"Hello Mistahays,
Congratulations on the new gin palace. Enjoy. I wouldn't mind paying the $10a gallon so much if i had a beauty like that.I wouldnt even worry about going anywhere i would just love to sit in it.Worth every penny(i mean cent!)
I can see the logic in your suggestions regarding a temporary gravity fed tank.I'm a bit worried about the practicalities of having a loose tank perched somewhere high enough on an open boat and blasting around Cardiff Bay at 25 - 30 knots which is when engine dies after a few minutes.
Could use the wife to hold it i suppose. I can see the point of why i married her then.
Watch for the News headlines and if you see "Suicide Boat Bombers blow up Cardiff Bay Yacht Club(Could you please ring the Club for me and explain it wasnt deliberate but that my wife must have dropped the tank!)lol.
Seriously i'll take that on board and see if i'm up to it. Good ideal in theory though.
The Tank sender plate is visible with engine cover removed so hope to have a couple of days leave and pull pick up filter out and clean. Just bought myself a compressor so good chance to blow out all fuel lines and carb innards etc.

Well many thanks for your help and Keep that Bourbon iv drip topped up.
Regards
Rod F}"
 
"Rod - no IV drips for your bo

"Rod - no IV drips for your boat... not safe. Works when i diagnose my brit cars (triumph, MG...)

Sounds like you are up for the diagnosis! Keep us posted. Good luck!"
 
no one`s mentioned the "An

no one`s mentioned the "Anti-syphon Valve"
If stuck partially closed you could have fuel starvation.
 
"Mistahays,
No Need to worry,

"Mistahays,
No Need to worry, I Have a great deal of respect for petrol(gas),especially in boats.Won't go down that line.
Bt Doctur,
I didn't know about an anti syphon valve on these, where should i be looking for it?.
Thanks to you guys on forum i have quite a few more ideals to try overcome this problem.
Regards
Rod F"
 
the 1st barbed fitting off the

the 1st barbed fitting off the tank feed. For testing purposes replace with a standard barb fitting.CG Regs. require a "Positive Shut-off" either by a anti-syphon or a manual valve at the tank.
 
"Thanks Guys,
I'll check

"Thanks Guys,
I'll check out the anti-syphon valve and other Fuel line issues over the week-end. Won't get to the water though. Too much to do at home.
Mike,
Ahh that old check valve ball haunts me still!Have you had problems with Carb/ accelerator pump. Do the id numbers 15396A-4 with 2702 stamped below that, mean anything to you?
I can't find anything to match in my parts manual to identify the accelerator pump contruction.
But i can't see any logic in there being one under the pump return spring on my carb. There is no seat for it to sit in, just a counterbored recess for the spring diameter to locate in?
According to the man i bought the boat off, Carb was supposed to have been a replacement from States(would make it about 5 years old now but not many hours use as i spent one season re-building engine, new crank, main & big end bearings + 1 piston & con-rod).And then one season with no problems.
Current Fuel problems started after de-winterising boat and getting it in water under load.
Rod F"
 
""Current Fuel problems st

""Current Fuel problems started after". Rod, as a step in getting ready did you fill the gas tank?
JW in Dixie"
 
"Ah, it just hit me! I cudda h

"Ah, it just hit me! I cudda had a V-8! If the vent hose isn't drooped and causing the problem, take it loose from the fuel tank and blow thru it. Sometimes Dirt Dobbers will build a mud nest in the fitting on the transom where the vent breathes. This would cause the symptoms you describe. Hope this helps. JW in Dixie"
 
"Gentlemen,
Didn't Get ro

"Gentlemen,
Didn't Get round to looking at boat on weekend. Apparently a rabbit hutch for "she who must be obeyed and daughter" had to take priority.But boat its still there for me to look forward to as its not going anywhere as it is.
Gas tank was left 3/4 full with added stabiliser over winter but no new fuel added since!
I will blow out vent hose and all other suggestions after i finish the rabbit hutch.
Rod F."
 
"she who must be obeyed&#3

"she who must be obeyed"

I've got one of those. I have no tools in my tool box or manuals with which fix it.
 
"David;
And if you try to ins

"David;
And if you try to install "Girlfriend 3.74" in place of "she who must be obeyed", you are in for a world of hurt, as the operating system will freeze up completely everytime you try to use it; plus all your system resources will be mysteriously frozen!

Rod"
 
"Last summer my boat ran into

"Last summer my boat ran into an issue in July.Ran 2 minutes,fell off plane for a few minutes,ran good again for 2 minutes.After lots of guesses, turned out to be obstruction in fuel line at top of tank at checkball.Sound familiar?....Todd"
 
"Thanks Todd,
I am working my

"Thanks Todd,
I am working my way back to your checkball suggestion. Given the age of my boat, i reckon this could be the problem area. I have stripped carb and cleaned and blown everything through with compressed air. All now "looks" good.
I am just waiting for the traditional UK holiday weekend rain to stop, then i can get out on the drive and into the engine bay.
Rod F.
" To Wives and Girlfriends"
May they never meet!"
 
Roderick Ferris
Sorry for th

Roderick Ferris
Sorry for the delay. Flu bug got me. The spring loaded rod you are referring to is the power valve circuit. All that does is dump raw fuel in when needed for acceleration over and above the accelerator pump. The pump ball should be located under the chevron type gasket that sits between the bowl and the venturi nozzles. All the check ball for the pump does is stop air from being ingested into the pump well on its return stroke so I can't see that being a high speed problem. Sounds to me that your problem is it the high speed circuit and that will be your high speed jets or fuel supply.
Bert
 
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