Logo
FULL SITE MENU

Overfueling 86 Bayliner trophy

U

uscgret

Member
"Hi everyone, I posted last fa

"Hi everyone, I posted last fall with this same problem. After replacing everything fuel related and spark related on the boat the problem is still the same.

I have a 1986 Bayliner Trophy with only 300 hours on it. I get it underway and go about a 1/4 mile and the plugs foul and I get a measurable amount of gas in the oil pan.

I have replaced EVERYTHING fuel related with new parts. I also replaced the distrib, coil, etc etc. Everything is in spec.

I need some good advice. It's a 260A small block chevy with a volvo penta set up. Rochester Qjet on top. I can turn both mix screws in to the bottom and the engine will not change pitch or die. Almost seems this thing would run without a carb at all. I had the original carb rebuilt twice and the put a brand new one on it to eliminate the idea that it was the carb. No Joy, same symptom.

Help"
 
"There should be a clear plast

"There should be a clear plastic hose running from the fuel pump to the carb flame arrestor. If you see fuel inside that plastic hose, that means the fuel pump has a perforated diaphraghm and the fuel is being diverted to the carb flame arrestor so that it does not reach the bilges and causes an explosion. However, you will get a very rich mixture and the engine will perform poorly or die.

Just wondering if this could be your problem. If it is, just replace the fuel pump and off you go."
 
"Sounds like a fuel pump to me

"Sounds like a fuel pump to me. Do as El P suggested, or better yet, if it is old and you do not know when it was replaced, I would just change it. Preventative maintenance, my pump only cost $50, and I changed it even before I tried starting the engine on my new to me boat.

Have a great day,

Rob."
 
"Fellas, evrything is new &#40

"Fellas, evrything is new (I understand that new may not be good) but...........I'm a wrench and can figure that if man made it, it will fail. so I bought two of everything, in some cases three, because the boat is worth it.

Problem stands, and when I say I bought all replacementment parts. How bout X 2 and in cases (carb) x 3 (if anyone needs a carb call me). I reset the timing and am going to 45ts plugs to see if that helps.

Other than that, next post will be a NEW 1986 trophy fisher for some lucky guy.

Highest regards,

Denny"
 
"Denny,

I also have a 1986

"Denny,

I also have a 1986 Small block Chevy, but the 225E. I'm not sure if we share the same carb or not, but if we do, I would be intetrested. Maybe someone on here knows?"
 
"Did you purchase a Marine fue

"Did you purchase a Marine fuel pump or a FP for a auto,,I purchased a FP from autoZone and it failed and was pumping gas into the block"
 
"Never, never, never use autom

"Never, never, never use automotive fuel pumps in marine engines. You are risking your life and others' by doing so."
 
"Hi fellas, long days at work

"Hi fellas, long days at work but I'm going to dive back in tommorrow. The fuel pump was a marine pump, I'm retired Coast Guard and have witnessed the results of short cuts. Only BBQ I want to see is on my back deck. Believe me.

I will install the plugs tommorrow after I change the oil/filter again (worried about oil viscosity with the gas run contamination. I'm putting in the 45ts plugs (hotter), new carb, will check timing/dwell, adjust carb and hopefully I've just been chasing my tail, but at this point.......dunno, will keep you posted.

When I reflect back on my problems...the boat sat for over 10 years. I pulled as much off the 144 gallon tank as I could, used sea foam to bring the remainder up and pumped in about 50 gallons (1/4 tank)(not even) lol of fresh hi oc fuel. Changed every filter except the one on my cigarette, all new lines, and lit her off. Since, I replaced fuel pump, anti syphon, all lines, all filters 20 times, had the carb built twice (Boat only has 300 hours on it since new off the floor of the detroit boat show), bought a new carb, and I still have the same symptoms.

I also leaned toward maybe a weak spark. Sooo New Distributor, coil, wires, points, cond, etc oh yeah and plugs 43t's.....

I think I might have had a bad fuel punch in the middle of fixing all the angles. Initially filters, then plugs fouling, hen I looked at the carb and FP like anyone would. What are the chances that I over reacted and should run a tank through it and despite the plugs and filters I would replace....just go at it????

ANYONE?

I'll keep you posted and thanx for all the work on this you guys.

Denny"
 
""I can turn both mix scre

""I can turn both mix screws in to the bottom and the engine will not change pitch or die. Almost seems this thing would run without a carb at all."

I just experienced the same symptom with my new carb and it turned out that the electric choke had no power so it was 'choking' all the time. I had a RQjet a number of years ago but I cannot remember how or if it was choked.
blush.gif
.

It is obvious from what you say that either the mixture becomes so rich that it will not support combustion or that the spark is too weak to lite the mix or that the timing is a long way off.

I think timing that far off would be evident from the get-go(???). I also think that a very rich mixture would be evident on start-up (true I think, see quote?).

Why the hotter plugs Denny? Was the engine running cold?

fwiw Tom"
 
"<font color=""0000ff"">[i]Soo

"<font color=""0000ff"">Sooo New Distributor, coil, wires, <font color=""ff0000"">points</font>, cond, etc oh yeah and plugs 43t's..... </font>

"Points??????". Those things should be banned in today's day and age, they are as inefficient as the Edison lamp.
thumbs_down.gif
"
 
"I agree El,,It was a purchase

"I agree El,,It was a purchase due to a long weekend and no marine parts available...Learned a lesson not to use auto parts instead of marine...never ever again"
 
"Hi Tom,
Sorry about the dela

"Hi Tom,
Sorry about the delay, been working on the boat like mad.

Put in hotter plugs to maybe boost the burn in the cylinders. I just replaced all wires and now have great spark to all 8 cylinders. Did a compression test and have 150 lbs across the board. Put on a new carb and I still seem to be overfueling a bit but no gas in the pan now. Just smells raw when running in the water. Held her at 4400 rpm on the voyage yesterday and it seemed to run ok but idles a little poor. I can't figure this thing out. It starts really hard (cranks like crazy but you have to give it wot to get it to fire.)Any ideas, I checked the choke and it's operating fine, fully open when hot. Any help would be appreciated.

Denny"
 
"Have you considered investing

"Have you considered investing in a Pertronix electronic ignition kit and sending the points and condenser to an antiques museum?
biggrin.gif
wink.gif


If it smells a lot like gas at idle and the choke is fully open, my guess is that the idle mixture may need further adjustment. I recall there are two idle mixtures screws to adjust. Attaching a vacuum gauge to the intake manifold while you are setting the idle mixture will be helpful. Check this link:

http://carburetor.fateback.com/Rochester_Quadrajet_Tuning.html

Also, I assume that the flame arrestor has been checked and it is clean."
 
"Opening the throttle to wide

"Opening the throttle to wide open is a technique frequently used to clear and start a flooded engine. It runs well at high rpm because it the idle circuit is not used at high rpm. The fumes at low rpm point to an idle jet overly rich mix or an extremely lean mix (unlikely).

Could also be that the float level is too high and that the needle/seat valve is not closing tightly enough and allowing fuel to spill over and enter the carb. A similar 'overflow' scenario can occur if the fuel pump is putting out too much pressure. I believe I am in the throes of solving this problem with my carb and I'll install an inline fuel regulator as a first step.

I have also been informed that if the idle speed screw is set too high, the idle mix screw will be overridden by the fuel scheduled by the advanced throttle, ie. the throttle plates begin to close. The plates should be wide open as possible to allow the idle mix screws to control the fuel supplied.

The way to set the idle mixture is to back off the idle speed screw until the engine will barely run. (This is to keep the throttle scheduled fuel out of the idle picture.) Then screw in (lean) the idle mix until the engine falters. Back out the idle mix until the engine runs better then starts to run worse (too rich). Screw it back in until the engine runs best. Now set the proper idle speed with the idle screw.

fwiw..Tom"
 
"Hello all this is my first po

"Hello all this is my first post here,I found your group trying to find an answer to a problem that has me pulling my hair out and I don't have that much to spare. So any suggestions would be appreciated.
I have a 1989 Holiday Mansion, I love this boat, bought it eight years ago and really haven't had any problems with it. Until last year when I found I was making oil (gas in oil) I have read here about others having similar problems but nothing seems to fit. The engine is a Volvo Penta sterndrive model AQ271C the block is a 350 chevy she has a 4 barrel Holley carb. The thing that I can't understand is that the boat is showing no other signs of a problem. I can leave her sitting for 2 weeks jump in tickle the key without touching the throtle and she will start within 2 or 3 revolutions. The boat runs flawlessly! Yet I keep getting gas in the oil.
The first thing I tried was replacing the fuel pump (marine of course). The problem continued, next I had the carb overhauled to the tune of $380.00 But still I am getting gas in the oil. I don't know what else to try!"
 
"Dan, while you may get some a

"Dan, while you may get some answers on this thread, you would do better if you started a new thread. Just click on the 'Start New Discussion' link at the top of the subjects page.

Cheers, Tom"
 
In case you come back here Dan

In case you come back here Dan..

There are only so many places that fuel can get into the oil. You've done the fuel pump already but I was willing to bet that was the source of the fuel because the engine is running properly. the next place is the carb. Over fuelling in the carb because of a stuck float or malfunctioning needle/seat valve is a possibility but that is usually accompanied by the engine not running well. I would be tempted to re-check the fuel pump.
 
"I installed the pertronix ign

"I installed the pertronix ignition, no avail. I am focusing on the carb (2nd new one) as the source of the problem. I am getting alot of fuel in the pan and after running at the dock for an hour or so, I lose 4 cylinders and the smell of raw fuej in the marina is strong from my exhaust. When I shut it down and restart I have to go to WOT to get it to fire, thus believing that the bowl is dumping fuel into the intake and draining after shut down. When I look down the carb when it's running, there is a larger amount of fuel going into the intake than it needs. Any and all adjustments to the mixture screws don't change the pitch or idle. My engine sits at a slight nose down attitude, maybe 10 degrees, so what I'm concluding is that the float isn't positioned correct for my application. I am going to attempt to remove the top of the carb while it's mounted and see if there's fuel in the bowl. If not, I'll know that the bowl is draining and the float is incorrect. Just thinking out loud and hoping this will help the next poor slob that has this headache and save him thousands of dollars in parts and labor. If anyone else has advice, it's all welcome. I'll keep you updated on my findings."
 
"RE: "attitude" of th

"RE: "attitude" of th eengine/carb. Your intital post indicated thathtis was qa porblem after running awhile... When running, what is the "attitude" (besides lousy:) ) of the engine? Re: 10 degree issue... Is this the original engine? Had it ever been removed/replaced? When I had my boat re-engined, the first engine that was shipped got returned since the wrong wedge was under the carb..."
 
"Hi Rob,

Didn't get a m

"Hi Rob,

Didn't get a moment to get down to the boat this evening, worked late.
I have no plate under the carb. 2nd owner since new off the detroit boat show floorroom with only 300 hours. The gent I got it from fully rigged it with the best gear on the market times 4 and put it in a marina. He wanted to charter. He said that at one point someother charter cap put something in the tank and he had problems. After that he had work done, tank scrubbed.....etc.. and was back and running but lost his taste for it after one trip, and here I am. Beautiful boat and fully rigged with no hours. so........if you read the thread.....I feel like I'm closing in but the boat has more new things on it than my diesel pickup, and the others a little mad. I'll research to see if it came with a wedge or not but with a 144 gal tank in the stern, and it's nearly empty the nose sits down further considerably. Thanx for the input mister, I do appreciate it. El must have the day off ;'/"
 
"Denny -

Just out of curios

"Denny -

Just out of curiosity, has the engine ever run correctly ? Did you acquire the problem with the boat ? Are you certain you are purchasing the correct carb and fuel pump ? If it's dumping too much fuel thru the throttle body... well... it's dumping too much fuel. No ignition issues there.. it's just dumping too much fuel and there are only a few things that could affect that."
 
"Jeff, good word..adopt.

Ye

"Jeff, good word..adopt.

Yes sir I have had this from day one. The "best" marine mechs around have replaced everything except the head, intake, and block.........

I'm a good wrench, have built 100 of these but it escapes me as well.

Dumping fuel is the issue, that's why I'm going after the carb.

Fuel pressure, manifold pressure.... everything is as spec. Even though it's the 2nd new carb it only leads me to believe that I'm getting 6 pounds of fuel pressure directly into the man at idle. Then bleeding down after shutdown which would put it in the pan.

I'm all ears (and I mean that respectfully)"
 
"Yeah, that's weird Denny.

"Yeah, that's weird Denny. I'd say stuck floats or too much pressure, but if pressure is in spec and the carb is new, that doesn't make sense. But then neither does replacing everything and still having the problem... unless the parts that are being replaced are the wrong ones to begin with.. that's why I asked about the carb."
 
I still can't figure this

I still can't figure this out. Would I have 150 lbs of compression across the board with a bad cam?? Only thing I can think of is THE CAM has turned into a pipe and I'm not getting the proper lift from the valves. Any ideas??
 
"Denny -

I've been thin

"Denny -

I've been thinking about your problem now and then. I can't imagine it is a cam problem, you'd most likely hear that and it wouldn't explain excess fuel flowing from the carb.

You mentioned a few posts back that you had no plate under the carb. I don't know the specs on your carb, but I'd imagine that if it is out of level by too many degrees the floats/valves won't seat properly and it would allow excess fuel. Certainly when you have a stuck float that is what happens.

What are the chances the pitch on the carb is not correct ? That would explain why replacing everything has not fixed the problem. You may simply need the proper wedge under the carb."
 
Hi Jeff thanks for the reply.

Hi Jeff thanks for the reply. I got with V penta directly and they said I had the proper carb and there was no wedge on the intake for this application. I put a clinometer on the throat of the carb and it sits 2 degrees down so that shouldn't be a problem. That's why I'm leaning toward the cam. I'm going to pull the valve covers and do run outs on each valve. That may tell us something.
 
"Jumping in late in the discus

"Jumping in late in the discussion, but a few hints.
The old 260 Volvo was not of the 'best'. Be sure You use Champion RV15YC4 spark plugs, check that You have the restrictions in the exhaust passage in the intake manifold gaskets(under the carb), be sure Your engine temp is correct. Replace thermostat and check that it seals properly. Too much 'leakage, and temp gets too low.
I do not think cam might be an issue. Perhaps high back-pressure in exhaust?"
 
"Morten, Glad you mentioned th

"Morten, Glad you mentioned that. As long as this vessel sat in the woods, anything could have crawled up the pipes. I'll pull the exhaust apart first and go from there. Great idea!!!! The outdrive was ground level due to flats and the factory flaps were chewed off the 290 drive.
Could be a restriction. I might owe you some cheer for the holidays. I'm on it and will report."
 
"Sorry Morten.

I'll rep

"Sorry Morten.

I'll replace the thermostat as well, wife won't need her meat thermo till christmas so it'll give me some time to diagnose that as well.

Hat's off mister. Great ideas!!! On it.

Denny"
 
"I was reading back this threa

"I was reading back this thread in my sleep last night and something about mortens advice knocked me out of bed. The rigid flaps on the exhaust port of the outdrive were missing when I got the boat. I replaced them. They seem to be extremely hard, (age or design). Is there a chance I created this problem by putting them back on. When the boat is running in the water, seems to have the correct amount of bubbles coming from the exhaust but....... How important are the flaps?? Should I remove them? The previous owner said the boat ran perfect before he stored it.

Just searching,

Denny"
 
Back
Top