Vapor lock fix?

I have a 96 Ski Nautique that seems to have a vapor lock problem. I replaced half the parts on the engine last year and thought it was fixed but it did it again this past weekend.   A couple of people have told me to put wood clothespins on the fuel line....does this really work to dicipate heat in the lines?   It does have metal fuel rails along each bank that could be getting to hot and vaporizing the fuel in the rail lines. Ive also heard some say to wrap the rail lines in aluminum foil to insulate them from the heat...does that work? If niether of these are good solutions then please advise how to get rid of the vapor lock problem?

Paul,
I agree with Eric that it's pretty hard if not impossible to vapor lock a marine engine. You just don't get temps under a dog house like you do under the hood of a car. Do explain the symptoms.

You haven't been listening to the PN gang have you? Clothes pins and aluminum foil?

What engine do you have?

Is it fuel injected? Is it a Protec engine?

Are you sure you're definitely getting ignition when the boat is not starting? I'd check for spark to make sure.

Oh and yes its fuel injected...multipoint...hence the metal fuel rails on each side.

are you running Ethanol in the gas?

No ethanol as far as I know...I buy regular medium grade fuel for the boat. Also I believe the fuel return line is for if the canister is recieving more fuel then its pumping....I dont think it returns air to the tank when the engine is turned off, in fact I would thing the check valve would act as a seal for the system and would actually prevent that from happening with the engine off.

paul96cc wrote: No ethanol as far as I know...I buy regular medium grade fuel for the boat. Also I believe the fuel return line is for if the canister is recieving more fuel then its pumping....I dont think it returns air to the tank when the engine is turned off, in fact I would thing the check valve would act as a seal for the system and would actually prevent that from happening with the engine off.

I had a similar problem a few years ago although I though it was a fuel delivery issue (pump or carb). I asked my mechanic who told me Ethanol has a much lower boiling point than gasoline and can cause a vapor lock symptoms. I ran the old gas out, replaced it with non-E gas and it never happened again.

i recently took 2 samples of eth gas and non eth gas, put them in a cup, after 4 days, the eth cup is half full or for some half empty. the other glass is still just a little shy of full

OK, so I just read that most gas is now 10% ethanol. So lets assume that is what im getting, I still have the vapor lock issue...any ideas on how to get rid of it?

paul96cc wrote: On a hot day if I run it for several hours and get the engine real hot, then park the boat and turn it off for around 45 minutes to an hour, when I go back to start it it will crank, sometimes fire for an instant....but it wont start and run.

Paul - If it was me I would just raise the dog house & let it cool off when you have it moored.

You could spend a bunch of money chasing this one down. Might be the nature of the beast. . .

What is the fuel pressure reading? That system is a full flow system. The pumps supply fuel to the rail and back to the tank through the return line. The fuel regulator keeps the required fuel pressure in the rail by diverting some fuel back the the tank. If the pump doesn't supply enough pressure the regulator will not open and the fuel in the rail may vaporize. The fuel pressure must be in spec for the system to work properly.

Reading a few Jeep forums (Pirate4x4 and Jeepsunlimited) it sounds like the Jeep main vapor lock symptom is rough idle at start up (Hot soak) and not no Start. This is partially solved with insulating the injectors from heat.

An interesting read on the Jeep TSB / Vapor locking....

http://www.jeepsunlimited.com/forums...ght=hesitating

and here is the tsb:
--------------------------------------------------------------------------------

Fuel System - Hot Start Misfire/MIL ON/DTC's/Rough Idle

NUMBER: 18-031-03

GROUP: Vehicle Performance

DATE: Sep. 05, 2003

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-027-02, DATED SEPTEMBER 06, 2002, WHICH SHOULD BE REMOVED FROM YOUR FILES. THIS IS A COMPLETE REVISION AND NO ********S HAVE BEEN USED TO HIGHLIGHT REVISIONS.

SUBJECT:
4.0L Rough Engine Idle After Restart Following A Hot Soak

OVERVIEW:

This bulletin involves the installation of a fuel injector insulator sleeve.

MODELS:
2000-2004 (TJ) Wrangler (Domestic and International Markets)
1999-2004 (WJ) Grand Cherokee (Domestic and International Markets)
2001-2004 (WG) Grand Cherokee (International Market)
2000-2001 (XJ) Jeep Cherokee (Domestic and International Markets)

NOTE: This bulletin applies to vehicles equipped with a 4.0L engine (sales code = ERH)

SYMPTOM/CONDITION:

Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32°C (90°F) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder # 3 Misfire.

This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector # 3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder # 3 until the fuel vapor is cleared of injector # 3. The insulator sleeve lowers the injector # 3 temperature to a point below which the fuel will not normally vaporize.

DIAGNOSIS:

1. If vehicle exhibits a rough idle, and if a misfire of cylinder # 3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.

PARTS REQUIRED

REPAIR PROCEDURE:

1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length.

2. Install one sleeve around injector # 3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.

3. Confirm sleeve is flush to intake manifold surface around injector.

4. Check injector # 3 wire and ensure that the injector is rotated to a 2 o'clock position (from driver's side of vehicle).

For those of you that say a EFI marine motor will not vapor lock are out to lunch! We have had many a problem with vapor lock particulary this time of the year. in some areas winter time fuel supply's are still being used. combine that with higher then usual air temps and a situation for vapor lock can occur. ways of diminishing the problem are to buy fuel from quality vendors such as Texaco, Shell or any of the big company's. Mom and pop gas stations tend to purchase low grade fuel that have been known to cause a vapor lock situation. Did anyone ask where in the country this problem is occcuring? elevation?
We fought this problem with the first EFI motors until PCM came out with the FCC. The FCC did not totally cure the situation but greatly dimished the problem. other causes are low performing fuel pumps or hoses that have become brittle. also the delivery hose inside the FCC can be a problem. Anti syphon valves need to be cleaned and inspected.
a quick way to get your motor running when the problem arises is to pour lake water over the low pressure pump this will cool down the pump and alow it to push cool fuel back into the FCC where the high pressure pump can pick it up and evacuate the vaporised fuel back to the tank.

the regulator will maintain or regulate your fuel pressure, if the spec calls for lets say 50-60 psi, it must be within that range, thats where a fuel pressure gauge comes in handy. somewhere on that rail there should be a schrader valve to tap into to check your pressure. im not up to date on the Ford regulators, but the Chevy regulators seem to be troublesome and will cause similar problems to what your describing. what bothers me is why all of a sudden and not from the get go? this may be one of those times of being a parts swapper and trying a regulator if you dont want to invest in a fuel pressure gauge, maybe one of the pumps doesnt like the heat and its dead heading and siezing the pump and when you releave the pressure it decides to work again??? who knows? really though, to troubleshoot this problem you are going to have to invest in a psi gauge, im crystal balling and so are you, put a gauge in line and see what happens and i think you will narrow down the problem, that pressure has to be there for those injectors to pop

I have a left field question for you. when this happens next, you should open the fuel fill cap for the tank and try to start it. If your tank is either creating vacuum or pressure due to not breathing correctly, you would get these symptoms. I know my hot rod did this when the vented fuel cap went bad and made me pull my hair out.