Fuel Line connector getting too hot

[Marcel Cloutier]

Hello everyone,
I have a 1999 40hp Tracker Pro Series by Mercury (SN 0G770127) which has been sitting for the past 2 years. I have finally gotten it running (carb cleaned, fuel pump rebuilt, new fuel filter and new bulb) however now I am having an issue with a certain fuel connector that is breaking.

It is a 90 degree connector (Part# 43335 or 433351) made of nylon. It screws directly into the side of the motor and connects a line to the fuel pump. The nipple going into the fuel line is breaking off. When it first happened I thought, old motor= old part. I replaced it and after about 2 minutes of running it happened again with the brand new part. I have also noticed both times that the fuel line (4.25") between the pump and motor gets extremely hot (can't touch it) and I think it is melting the nylon causing the part to break.

Now, for the questions...
1. Does anyone know why this is happening? Water is running through the engine according to the tell-tale. I don't know if it should be getting that hot or not but before I keep melting parts at $5.00 a piece I figured I would ask first.
2. Does anyone know where I can get the same part in metal? I have never been a fan of plastic parts on any machine, except Glock.

I'll start with this, it will probably lead to more questions. Thank you in advance for any help you can give me.

 

[alldodge]

Do you have the electric or mechanical fuel pump?
Thinking the mechanical pump will not over heat but the electrical one could

 

[sam am I]

It's the mech fuel pump's pressure/vac tap fitting.....



Merc taps into the lower side of a particular cylinder and uses pressure/vac being created under the piston from and as the piston's stoke to actuate the diaphragm of the fuel pump. So no, no water flow right there per-se as the tap is threaded into and just behind (crank side) the reed block.....

Too hot to touch is a little concerning however, that is the intake side and it should be relatively cooler than the top end...Wondering if a bit of hot exhaust is leaking from the top end.

What the compression on the cylinders? Perhaps do a leak down as well....

In the mean time, I shutter to said it, replace it with brass and run it but, I have a feeling something isn't right to be getting that hot in that area. Especially if the factory part is nylon and there isn't any service bullion's calling for it to be replaced with brass.

 

[Marcel Cloutier]

All Dodge...It is the mechanical version.

Sam I am...You are correct. It is tapped into the top cylinder Not sure where it would be leaking exhaust up top but I will look again. I do not know how to do a compression test and I probably don't have the tool for it. What is a "leak down". I did notice that at the bottom of my carburetor I had a small drip while it was running. Did not have a strong smell of gasoline just a very faint smell. More like water with gas mixed in. Just a small drip. I don't like plastic parts but I do agree with you that if the manufacturer put it there they expected or tested it to work.
Once again the nipple that goes into the fuel line is where it is breaking. When it does break I am getting a good puff of air through the fitting from the cylinder but of course I shut it down pretty quick after it breaks.

I would like to try to fix this myself but if I need to go see a mechanic don't hesitate to tell me...
Thanks for the help.

 

[sam am I]

That pic above isn't your type of block but, it's the general idea/concept merc uses I should point out

It is tapped into the top cylinder

The "Pulse Hose" should be tapped under the piston (crank shaft/case side). Top end would be HOT HOT exhaust gases and 120+ PSI. Underside/intake/crankshaft side is something like +/- 3-6 psi if I recall right

Not sure where it would be leaking exhaust up top but I will look again.

If its from compression leaks, It would be a piston ring or cylinder wall issue..........Thinking maybe blow-by

I do not know how to do a compression test and I probably don't have the tool for it. What is a "leak down".

Google or search here, tons of topics here on this

When it does break I am getting a good puff of air through the fitting from the cylinder

Yes, that's the pressure/vac (+/- 3-6psi) the piston makes as it draws in and then pressurizes the fuel/air mix. This pressurized fuel then squirts up top.

I shut it down pretty quick after it breaks.

It won't hurt the motor, that cylinder will be a little sluggish thou

I would like to try to fix this myself but if I need to go see a mechanic don't hesitate to tell me...

Check here on topics but if not comfortable find a good trustable/knowledgeable mech. He can verify based on experience if it's too hot then most likely do both compression and leak down and at least tell you the cylinder is okay or not

Thanks for the help.

You're quite welcome

 

[Marcel Cloutier]

Ok Sam am I, I bought a tester and checked the motor. I am getting top to bottom, 90, 90 & 85/86 so within the tolerance. I also did a spark test just for the heck of it and am getting good spark but changed my plugs anyway since they looked kind of cruddy.

I guess I'm asking now what you think of the compression level and if you have any other ideas or checks I can make. If you say leak test, we will have to wait until next payday as I have run out of fun money to by the leak tester...haha.

Thanks again.

 

[James R]

If your measurement of the comps is correct it is ready for a rebuild. If this has been in salt water you could have all kinds of cooling problems. I think I would get a second opinion on the comps.

 

[Marcel Cloutier]

I have not put it in salt water but can't say if the previous owner did. I have had it for four years and it sat for 2 after it wouldn't start and I bought a kayak. Ready to get back to running the lakes so I'm working on it.

As far as the comps, I watched a couple of videos on how to do it and went out and bought a tester today so it is brand new. Seems pretty easy and I checked each cylinder twice. I have also read quite a bit on here about compression and they range from 120ish down to 80ish and most say that if they are all within 10 psi of each other it should be good. Not sure if this is correct but its on this forum...

still trying to figure out why the nylon piece is breaking though and why it is getting so hot on the side of the motor.

By rebuild I assume you mean the piston rings and such?

Thanks for the reply though.

 

[sam am I]

still trying to figure out why the nylon piece is breaking though and why it is getting so hot on the side of the motor.

Me too, I'm just guessing my best guess what might make it so hot there.............Blow-by, hot exhaust leaking past the rings is my best guess.

Can you get a IR temp gun and shoot the block and possibly trace the origin of the heat? Is it radiating down to this area from somewhere up top? Is the origin local to that area and such?

I have a cheapo IR gun that has a "scan" feature. You can sweep slowly with it, back and forth, up and down and watch the readings and sorta get an idea of the origin being of course the highest temp reading

 

[racerone]

I would say that this is for a water cooled fuel pump.------Water is coming out this fitting when you start the motor , yes or no ?------Sounds like you may need to look at engine cooling issues.

 

[sam am I]

When it does break I am getting a good puff of air through the fitting

Water cooled fuel pump? Well who knew..........:facepalm:

 

[Marcel Cloutier]

No offense but that's funny right there... Even for a rookie shade tree mechanic like me.

 

[Marcel Cloutier]

No Title

Sam am I, I probably should have put these on earlier but here they are anyway. In looking at the picture of the fuel line closer I can see 2 small holes or indentions just behind the line to the right, which I did not notice while I was working on it. Without doing a leak down test yet could these possibly be an issue; allowing hot exhaust blow right on the line causing it to over heat? If you see anything else in the picture please let me know. Thanks again.

 

[sam am I]

I don't see the holes/indents........If you fired it up, can you feel hot gas coming out of them?

The nipple sure looks like it got hot thou.....you're right. Hot gas going through it is still my best guess. The threads look like they've been heated (by the block) but perhaps not as much what looks like a hotter flow through the connector (gases) that melted the nipple...........weird!!

If that is the case,

As I understand/experienced this pump, the volume of flow through the pulse hose/connectors (items #14, #18) and onto the fuel pump's diaphragm face is really really low (almost a pulsed static amount).......BUT If you have a leak on the pulse hose side of the fuel pump (not the fuel side), the air/gases driving the diaphragm and leaking out would allow a higher volumes of gases to flow in those components (the two connetors-14's and the pulse hose-18).

If the flow was hot'ish gases, that would allow the component to heat even more........but, from the inside and especially where it necks down into the nipple and not necessarily as much as the threads/external area's of the same components. As it sorta appears to be by your pictures its more heating from the inside.......

Perhaps you have a bad gasket/seal between diaphragm 3 and housing 13 leaking the pulsed gases? Can you do a quick leak down test on this side of pulse hose/fuel pump?


or perhaps


Do you have a fuel pressure gauge on the boat? If 3 and 13 was leaking gases, I'd reckon with only half (item #10 seals the left/other half of the other diaphragm #9 that also helps to pump the fuel) the fuel pump's diaphragm working, the fuel pressure should be lower than spec'd.

Short of just going to brass and looking the other way (not in my spirit to ever do that), I'm sorta stumped if everything is checking out.

 

[Marcel Cloutier]

I will try some of these out in a few days...back to work time. Thanks for all the help and I will leak down test it next. I have not fired it back up yet since the piece broke, only turned it over for the compression test. Please keep an eye on this topic as I will put the results up after the tests.

 

[sam am I]

If its blow-by, excessive blow-by, perhaps excessive heat/pressure took out a gasket or is just plain exceeding the fuel pumps design pressure and is pushing too much hot gas into the fitting.............just guessing still

You mentioned a "good puff when it broke" HOW good of a puff? Too good of a puff perhaps?

Can you take a compression test measurement on that fuel pump pulse hose port you have opened up?

As i mentioned above, I recall the lower side/reed valve side is not suppose to be much above like 2 - 6 psi @ idle if i recall the spec right. This port should be around this valve.....

 

[Marcel Cloutier]

Ok sam am I, I have some good news and some bad news.
First the good news...I found the problem.
Bad news...I don't know why it is happening or how to fix it.

I did a leak test and found that I am at 30% leak when at TDC in all three cylinders. I can hear very faint leakage through the carburetor in all three. If not at TDC I have the air coming out of the suspect fitting. When I turn the flywheel and get exactly TDC, there is no air coming out of the fitting.

Now, not at all holding you accountable, but since you said it would not hurt to run the motor with that fitting and hose not connected; I tried that so that I could do an IR temp check. Here is the interesting part. While running the motor without the fitting in, I can see into the opening on the side of the cylinder. The motor will run for a short time before stalling out but during that time I can see small puffs of air coming from the opening. These are not strong and are not hot as I can hold my hand up to them. Now every so often there is a small "explosion"/ "flame up"/ "back fire" in the opening and I can see flame inside. Now obviously after a few of these, a nylon nipple will melt and break so there in lies my problem. The IR reading after these was only 81 degrees but the motor had also not fully warmed up yet.

Now your turn...

Any idea what this is called and/or how to fix it? If you need more information, ask away. I also have a lot of very white heavy exhaust smoke when it is running but I attribute that to the SeaFoam I have in the fuel (I put a whole can in the tank with 5 gallons of E-free gas when I first started this adventure thinking it was just a dirty carburetor.)

Please let me know your thoughts and thank you again.

 

[sam am I]

How cool..........I mean, wow! Fire in the hole!!! Look out!!!! Hehehe. Wonder what this would look like without the reed valves? Bet you'd burn some eyebrows off..............Been there done that, built a HP Chevy 327 back in the day and it backfired up through carb with my face in the way.

Ummmm, well I'd guess again the explosion your seeing is that of

1) Something is sparking somehow (crank shaft hitting a lost set of keys?) in that lower side hole igniting the air fuel mixture (low odds)

or


2) Super heated fiery gases from the top end is blowing-by and is igniting the lower end's fuel air mixture (higher odds)....Why just randomly happening? Maybe loose worn rings, lower cylinder wall wear, piston skirt wear all sorta in a randomly moving around reciprocation frenzy.

With this and lower compression and leak-down of 30% is saying rebuild time sorry to say.

So having fire possibly shooting up into this hose isn't too good, especially since this hose leads directly to a fuel pump whos thin rubber diaphragm is the only thing between this pipeline'd hose shooting fire and a possible fiery 4th of July early!!

So.....perhaps (strongly suggesting) as a better safer work around then going to a brass fitting, is to just plug off the hole and just run a electric fuel pump designed for the motor/boat, you know, until you get it fixed..........

Must say, this was an interesting issue to say the least.....wonder if merc's eng's ever thought this one could up? Probably not since fiery hot gases that could possibly get to and burn away at the fuel pump's rubber diaphragm would have probably prevented the fuel pump's design as we currently know it.

 

[ondarvr]

What you described as a small puff coming out is common when the motor is running lean at idle, the sneeze is the fuel combusting in the crankcase instead of the combustion chamber. The sneeze can heat the pulse hose and blow it off the fitting or damage the fitting.

If you put your hand in front of that carb and restrict the air flow a little it should stop sneezing and run better. If it is a carb issue you need to get it fixed right away or you could do damage to the motor.

The motor could still be worn to the point of blow by being a problem, but maybe not. Compression gauges tend to read differently at times, sometimes significantly, so just having low readings isn't always the sign of a worn out motor.

 

[Marcel Cloutier]

sam am I, thank you so much for your help on this. I'm not sure I'm ready for a rebuild. This is really my very first engine job. I am having fun learning but as with any hobby it is getting expensive. I agree with you that I DO NOT want to be running down the lake with fire breathing into my fuel pump. I'm not against plugging it off an switching to an electric pump, however I don't like that this is happening and even though I don't know much, I know that explosions happening where they aren't supposed to only leads to more problems. Haha.

ondarvr- What you described is exactly what it is doing. Already broke 2 fittings. I'm holding onto my last one until I can get this figured out. Now, by carb issue...do you mean get a whole new carb or can I just rebuild it like I did with the fuel pump. What (if you know) is causing the combustion in the crankcase? Doesn't it need an ignition source of some kind?

Again, this is my first engine I have ever worked on so please bear with me on my ignorance. I am comfortable enough working on the carb now so I can either rebuild it or replace it, whatever is the better choice, however it might be awhile before that gets done.

Lastly, if it is running "lean" is this an adjustment I can make or is it the additive I put in the fuel? Man I feel dumb, but I won't know unless I ask...

Thank you guys so much for your patience.