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HELP. Engine Dies after a minute of WOT

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Moonfisher1

New member
Hello to all, I've worked on boats for years but this one has me stumped. I have a 1985 Grady White 227 22' Seafarer with a 200 HP Mercruiser 305 2bbl mated to an Alpha One. It ran fine the year before last. I replaced the lower half of the outdrive last spring and tested it with a 20 minute run in the river. Worked fine, put boat on trailer and never used it again last year. I put Stabilizer in the tank with about 1/4 tank fogged the engine and winterized engine/outdrive. This spring, I put in two bottles of dry gas (as usual) changed the Cap and Rotor and fuel/water separator. From my slip, I start the engine and let warm up. I back out and drive about 1/2 mile at 6 Knots to open water. Once there, I WOT for about 20-30 seonds and the boat bogs down and dies. I emptied the fuel water separator 4 times in a 20 minute test run. I can idle fine but the boat dies with the RPMs at or above 3000 for 20-30 seconds. I've gone to a larger 10 micron fuel water separator and installed a rebuilt carb but neither helped. I was about to change out the fuel pump but I don't have a pressure gauge to see if it has 3-6 psi. I haven't checked the anti-siphon valve or the tank pick up screen yet. I ran the boat with the tank cap off so it is not the vent. I did have a bees nest under the helm that I sprayed with wasp killer and I'm wondering if I've corroded an ignition circuit? After the boat stalls out, it restarts instantly. It doesn't matter if the seas are calm or rough. It does the same every time. 20-30 seconds of WOT then stalls or looses 90% power but still idles. I'm planning to try a hose and an alternative source of fuel tomorrow to eliminate the fuel tank as a culprit. I do not think there is any way the newly rebuilt lower unit could be a factor. Any and all comments welcome. Thank you.
 
There are several things to do to see if you are running out of fuel but they require a second person and may be a bit to dangerous to type here



Hook up a second gas tank with fresh gas to the input connection of the water seperator. Prefferably a outboard style tank (6 gallon type)

Try that, if that does not solve the problem then fuel pump next, it is obviously running out of fuel...
 
kghost said:
There are several things to do to see if you are running out of fuel but they require a second person and may be a bit to dangerous to type here



Hook up a second gas tank with fresh gas to the input connection of the water seperator. Prefferably a outboard style tank (6 gallon type)

Try that, if that does not solve the problem then fuel pump next, it is obviously running out of fuel...
Click to expand...


kghost, Thanks for the response. When I said " I'm planning to try a hose and an alternative source of fuel tomorrow to eliminate the fuel tank as a culprit." Doing what you said was my intention. I like your outboard style tank idea for the temporary gas source. I'll try that this evening.
 
Master Mechanic,
Thank you for the reply.
When I said " I ran the boat with the tank cap off so it is not the vent." I eliminated that possibility.
I need a fuel pressure gauge to check the 4-7 PSI range you've mentioned so I'll look for one today.
Should the pressure be tested with the gauge as a "dead end" while I just crank the engine over a few times or does it need to be in line (between the pump and the carb) with the engine running ?
 
Moonfisher1 said:
Should the pressure be tested with the gauge as a "dead end" while I just crank the engine over a few times or does it need to be in line (between the pump and the carb) with the engine running ?
Click to expand...
No need to "dead end" it. The carburetor's needle/seat will create the resistance that will cause the pressure that you will be seeing.
Just find a temporary means of connecting the pressure gauge.

Have you considered that the ignition coil may be acting up as it generates heat?


Have you pulled the fuel tank pick-up tube, and looked at the screened section?


As for fuel delivery..... do you own a Tempo Oil Boy fluid extractor?
If so, connect the Oil Boy up to your fuel line just prior to the fuel pump.
See how easily it can pull fuel from the tank, through the anti-siphon valve, through the fuel filter and up to the Oil Boy.
If it pulls easily, IMO, there's no need for the auxiliary fuel tank.


.
 
The best way to test for fuel pressure is to T the guage into the fuel line between the pump and the carb.

If you can get a fuel line that has the threaded fitting for the carb to pump, does not have to be for the merc system but should fit the carb and fuel pump. cut it and the guage should be tee'd into it.

This youtube video is for a 1972 truck but it shows the T I am refering to.........

http://www.youtube.com/watch?v=l_7F8PiQNiY
 
Rick,
Thanks for the input. I do not have an "Oil Boy" but understand the mechanics/theory of the vacuum test procedure.
The coil is working again in a minute after the stalling, can it cool off that quickly?
If my "alternative fuel source test " passes this evening, I'll go to looking at the fuel line and pick up screen in the tank as well as determining a safe way( Spark proof) (Oil boy?) to clean the bottom of a full tank of fuel.
I have about 90 gallons at 7/8 full.
Tank is aluminum.

kghost,
Thank you,
I'll look at the fuel pump, it's output pressure and fuel supply to the filter after the alternative fuel source test this evening. I'll post the results.
Good video/visual aid.
 
a vacuum gauge Tee'ed into the suction line of the fuel pump will give you a very good indication of any issues on the supply side.
 
kimcrwbr1 said:
Pull the fuel line at the carb and stick it into a quart jar and crank on the motor and see if it gets a good flow low pressure high volume?
Click to expand...

Thank you,
I did that the first time I pulled the carb. I got 3 good squirts that might equal 1/2 pint? I was checking for water in the fuel at the time. I cannot judge pressure by eye and I don't have a gauge set up yet. I'm going to try a bottle of good gas to feed the fuel water separator those evening. If it runs good , I know it is in the hose and tank. If it runs bad then I'll invest in a fuel pressure gauge and associated fittings.
 
Not necessary,,,,,,,that will only tell you the pump works and gas is pumped at cranking speeds...........That is not your problem..........yours is at high rpms......either low or no pressure at high rpms or restriction of fuel from tank for now.....

I would imagine the pump would pull ~ 10-12 inches of hg but that is a guess

Outboards pull I think between 6-8 inches.........
 
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kghost said:
Not necessary,,,,,,,that will only tell you the pump works and gas is pumped at cranking speeds...........That is not your problem..........yours is at high rpms......either low or no pressure at high rpms or restriction of fuel from tank for now.....

I would imagine the pump would pull ~ 10-12 inches of hg but that is a guess

Outboards pull I think between 6-8 inches.........
Click to expand...


Thank you for that input. I'm about to head home to test with a separate fuel source to the filter. I'll take the next step based on its results.
This is a great forum and I appreciate all of the ideas provided.
 
Nowhere near that much vacuum....we shoot for 3" Hg in a new or repower installation with clean filters...5" Hg max at WOT...

If your pump is creating 10-12" Hg, you have a severe restriction....the gauge is also very handy to detect the "crud covers the pickup tube strainer" scenario...if you have ever experienced it - well, enough said.
 
makomark said:
Nowhere near that much vacuum....we shoot for 3" Hg in a new or repower installation with clean filters...5" Hg max at WOT...

If your pump is creating 10-12" Hg, you have a severe restriction....the gauge is also very handy to detect the "crud covers the pickup tube strainer" scenario...if you have ever experienced it - well, enough said.
Click to expand...



Thanks for the clarification, It has been a while since I did a vacuum check on anything......I do remember the outboard number around 4 now that you mention it.
 
Update to all,
Problem solved. It was a badly swollen fuel line.(Ethanol damage?)
Details: I used a metal gasoline safety can with the spring closing lid along with a section of fuel line and a washcloth to seal it in place/avoid splashing gas. I attached the other end to the inlet on the fuel water separator (Now a "Tall" 10 micron). The boat ran better than ever and I picked up 400 RPMs at WOT (Rebuilt carb most likely). Now, the fuel line ran about 2 feet in length before it passed through a bulkhead going forward towards the fuel tank. In this area the fuel line looked ok. I opened the 8" round access hatch in the deck which is about 12" forward of the bulkhead mentioned. The fuel line leaves the tank at about a 90 degree angle in relation to the bulkhead. The fuel line a was visibly swollen at the clamp. Using fingers to feel back it became apparent that the outer jacket of the fuel hose had split and bunched up like an accordion. The inner hose had expanded and kinked itself. I cut the hose in the engine compartment close to the bulkhead and pulled out the mess/glob of rubber and nylon reinforcing. ( I should have photographed it) . I removed the anti siphon valve and checked it/worked it, reinstalled it with teflon tape. I installed a new fuel line with double SS clamps at each end. Test drive again, no leaks and running strong. I'll reseal the hole in the bulkhead with silicone today.

Thanks to all for their input.

Have a good safe season.
 
I used a metal gasoline safety can with the spring closing lid along with a section of fuel line and a washcloth to seal it in place/avoid splashing gas.
Click to expand...
That's one big arse Molitov Cocktail! With all the right conditions it would have vaporized you and the boat.
 
guyjg said:
That's one big arse Molitov Cocktail! With all the right conditions it would have vaporized you and the boat.
Click to expand...

I think this hose could have caused a much bigger problem. The safety can approach to the temporary fuel source was not much of a risk.
 

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Agreed, already inspected. The tank connections are good for both. The vent hose is clear. The fuel and vent lines are visable at the filler/hooded vent and appear in good condition and secure. The deck access hatch at that end of the tank was not watertight.
I'm thinking that various cleaners etc... over the course of 28 years took it's toll on the outside of the hose while the inside of the hose dealt with absorption of gasoline, water, alcohol, stabil, ethanol and whatever else was put in the fuel tank.
 
guyjg said:
That's one big arse Molitov Cocktail! With all the right conditions it would have vaporized you and the boat.
Click to expand...

Guyjg , I took a video that I thought I'd share showing the Fuel can set up. The 5 gallon gas can only had 2 gallons of gas in it and the washcloth rag didn't even get wet. That was a good observation on your part and I can imagine what you saw in your mind's eye. Enjoy the video ( if I can attach it) and have a great summer. http://www.youtube.com/channel/UCFa1ycbAfmU_q94pgQieg6A
 
Glad it worked safely. I just imagined the rag soaking up the fuel and a static spark igniting the fumes. My brother-in-law blew up his house w/a rag soaked w/gas cleaning glue off of the kitchen floor. It ignited right when he was standing in front of the open FR door...blew him out into the yard. He had massive burns all over, nearly died...DR said he would overnight but he survived. An Army medic on leave was next door and wrapped him in wet clean towels...must have done the trick.
 
Yes.
The inner rubber and the nylon reinforcement outside of it remained intact.
The mess you see is the outer jacketing which is applied in a separate step during the manufacturing process.
I used pliers to grab and pull the inner out of the bulkhead and up out of the deck hatch which made it look even worse.
 
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