Vapor lock issues

[alwayswrenching]

I have been hearing a lot about vapor locking lately. Currently my 02 bryant 198 vapor locked for 2 hrs...ugh so i been working on a idea. Thought i might get some opinions or discussion. Thinking of installing an electric water pump. Use a thermostatic switch when key is off to cool engine to prevent vapor lock

 

[achris]

... my 02 bryant 198 ...

Tells us nothing about the engine.

How about, engine serial number, engine year, engine model.

Year and type of boat is completely meaningless.

Chris......

 

[Scott Danforth]

in addition to Chris's comments, i seriously doubt its vapor lock.

 

[alwayswrenching]

02 bryant 198 5.0L this unit has a jasper reman marine eng. last weekend when unit vapor locked i removed fuel line from tbi...cycled key many times and got little to no fuel from line..if I have read correctly the fuel pump in the fuel cooler is poor at purging air from fuel system. Installed lift pump before fuel filter. If this does not help i was thinking og converting this SB Chevy to an electric water pump and controling with relay to run after key off until 160 deg block temp.

 

[Bondo]

cycled key many times and got little to no fuel from line..

Ayuh,..... This tells me, you have a restriction in the fuel system, 'tween the tank, 'n motor,......

I'd start by examinin' the Contents of the fuel filter for clues,....

 

[Scott Danforth]

02 bryant 198 5.0L this unit has a jasper reman marine eng. last weekend when unit vapor locked i removed fuel line from tbi...cycled key many times and got little to no fuel from line..if I have read correctly the fuel pump in the fuel cooler is poor at purging air from fuel system. Installed lift pump before fuel filter. If this does not help i was thinking og converting this SB Chevy to an electric water pump and controling with relay to run after key off until 160 deg block temp.

you dont have vapor lock. the only marine fuel system that may or may not suffer from vapor lock that I have ever encountered was a generator.(poor design by generator manufacturer that was later corrected)

the pump works as intended if the pump is in working order, your fuel filter is regularly maintained and you dont have a plugged AS valve

you most likely have a restriction like Bondo stated

why over-complicate a very simple and robust motor system by adding a bunch of bypass valves, an electric raw water pump AND an electric circulating pump (that needs to be marine rated and they dont exist) and you would still have the fuel system restriction.

 

[alwayswrenching]

Bondo . Fuel filter was new when motor was installed about 6 runnings hours ago...i removed and install new again just so i could cut and inspect. Did not find anything alarming in inside.


Scott im not trying to complicate as system im looking to enjoy boating but this new to me boat and i havent reached an agreement yet. Symptoms of vapor lock are here..when you try to start after 1-2 hrs of cool down engine will start and die...eventually will run and surge at idle then smoothout and be fine...if i had o2 sensors we could watch them for indications of lean...not sure how else to prove vapor lock.. as for AS valve i would like to inspect. I have no idea where that is on a bryant or how to get to the fuel tank under front of unit

 

[Bondo]

Ayuh,..... Water, 'n crap can get into the fuel system in many ways, in 6 hours, or in 6 minutes,.....

Ya don't cut open a fuel filter, ya dump it's contents into a clear vessel, let it settle, 'n look,.....

Hook a remote tank of clean fresh gasoline to the fuel pump/ fuel filter, 'n see if it behaves properly,.....
If it does, ya got a fuel tank/ plumbin' problem,....

 

[alwayswrenching]

Give a little credit..i didnt use a sawzall i used a chain pipe cutter. I wanted to see if debris was in filter from tank. With ethonal in gas the vapor lock seems realistic...if hot engine water drains back to fuel cooler and boils ethonal. With no way to bleed vapor out of system. The electric water pump seemed like a good conversation to solve an issue

 

[Bondo]

.if hot engine water drains back to fuel cooler and boils ethonal. With no way to bleed vapor out of system. The electric water pump seemed like a good conversation to solve an issue

Except the odds are 100:1 that it ain't vapor lockin',......

Boat motors run stone cold, compared to a car motor,.....

Hot water don't sink, it rises,....

 

[alwayswrenching]

Temp gauge on current engine runs 190 deg. According to research from mercrusier the block water can drain back through cooler and cause issue. If i found correct info. It is an open water system with engine higher than source gravity can let water flow backwards thru cooler

 

[Scott Danforth]

if you are running 190 degrees, either you need a new raw water pump, you have the wrong thermostat or your gauge is wrong.

you should have a 160 degree thermostat and be running about 160-165F

the symtoms you describe are plugged or bad Anti-Siphon valve

as stated before, you dont have vapor lock

not sure what research you are doing, however it doesnt happen. if you dont believe me, look at my profile on Linked In and see how many current and former Mercruiser engineers are on it that I know.

 

[alwayswrenching]

Im not looking to prove anyone wrong. Its just what information i have found. This is the exact reason i wanted to ask about the electric water pump. I am very well rounded in diesel and automotive paltforms. This is my first inboard boat. The engine and operating system looks very similar to an 1990 era engines. Where do would a guy find asv valve on this boat. 02 bryant 198 with fuel tank in bow area.

 

[Scott Danforth]

The anti siphon valve is the check valve in the hose barb on the fuel tank

 

[achris]

If ASV means anti-syphon valve, then it's usually the barb fitting on the tank that the fuel line connects to.

Being 'well rounded' in diesel and automotive does not make you a marine expect. Don't argue with people who ARE marine engine experts.They are just as likely to say 'bugger you', and not bother responding to you again (I know, because that's what I do if someone wants to argue points with me about things I have been working with for over 30 years.)

So, having worked on MANY boats over those 30 years, I can tell you, marine engines do not suffer from vapour lock, and adding a water circ pump is not going to fix a thing. Your problem is elsewhere. Have you done as suggested and taken a 20 litre remote tank out and connected that up? (FWIW, that should be the first step in diagnosing this sort of problem.)

And apart from '5.0L' we know near nothing else about this engine. Is it a 2bbl, 4 bbl, EFI or MPI. Electric fuel pump, mechanical fule pump? How about posting the engine serial number....

Chris......

 

[alwayswrenching]

Chris..i have given all the info i know of from the boat. Minus a haul number. This unit has a jasper reman engine in it. If there is a number on it to help you plz help me get you that info. Its a 5.0l tbi. In a 2002 bryant 198 br.
The fuel tank is located in the bow area if i have been told correctly. How do you access the tank?

 

[achris]

FORGET THE BOAT! Not the lest bit interested in the boat. Boats aren't like cars where the 'car' maker is the engine maker. Where a Ford car will have a Ford engine, and Chrysler car will have a Chrysler engine (except my Toyota, which has a GM engine :facepalm. Boat makers make hulls (and only hulls), then they buy in the engines, from either Merc or Volvo, for inboards (who actually buy in the base engines from GM). Your engine will be the same as in THOUSANDS of other boats, and likewise, an '02 Bryant 198BR' could have a 4, V6, V8 from Merc or Volvo, or it could come configured for an outboard, in which case it would have one of up to 8 different brands of engine.

And here's another issue. In 2002, Merc were only releasing MPI or 2bbl carbed engines, so the ENGINE can't be 02... If TBI, likely late 90's...

There should be an engine serial number SOMEWHERE. Usually on the engine cover (on the carb/throttle body), or on an ali tag just near the starter motor.

A 'reman engine' is only the long block. All the bolt ons will be from the original engine, which will include the engine cover and if the swap was done properly, the ali tag will have been moved across also....

As least 'TBI' does tell us a few things. Now, does it have VST or Cool-fuel? (How many hoses on the fuel filter?)

Chris......

 

[alwayswrenching]

3 hoses on fuel filter

 

[achris]

3 hoses on fuel filter

Cool-fuel. The fuel pump is already water cooled. And it's the first water to come from the drive and, there's a check valve in the line before the cool-fuel unit to stop hot water running back down to the fuel system after shut off. (And even if there wasn't, water can't flow back down through the water pump impeller unless it's seriously damaged, in which case, your fuel getting too warm will be the least of your problems.)

Your problem is not vapour lock. It's more likely a supply (lack of) problem. Try the remote tank test... Also, check the fuel filter housing for cracks at the fittings. You may have to remove the housing to do a proper inspection. It's such a problem that Merc released a parts bulletin about it a while ago.

Chris.....

 

[alwayswrenching]

So i did some digging and found a engine s/n
0M080230.
i have tried to access the fuel tank by removing covers or partitions the only area i havent tried crawling in is the under floor storage.