Progress! But still too hard to start on water - 96 Challenger

[mejim707]

So yesterday I pulled apart the fuel system;

1. I removed all hoses (they were not the gray tempo ones just old crusty ones).
2. I removed and inspected the pickup, it was perfectly clean. And the float and gas gauge work.
3. I removed the fuel selector. I could blow air through it and it worked as expected in the 3 modes, On, Off, Reserve.
4. I checked the return lines. There are two tie wraps at the "Y" of the return. That's the only place I would expect the air to intrude since everything else was locked down with proper hose clamps.
5. I pressurized the tank a bit, not to the full 5PSI because I have about half a tank, but the pressure did hold. I'm going to fill the tank today and pressurize to 5PSI to be 100% confident there is no air leak for a potential of air intrusion.

This all brought me to happening upon something as I looked over the parts diagram. I was reading the part names then saw that the pulse hose was called a "formed hose". This took me down a path researching the pulse hose.

The one I have is a clear, flexible and flimsy hose that's responsible for the pulse. I never thought anything of it because this is the hose the previous owner had on it so I thought this was normal until I saw that name on the parts list.

After researching I find out that hose needs to be a strong, reinforced hose or it could kink / collapse and prevent proper pulse to the carbs!!!!

COULD THIS BE MY ISSUE ALL ALONG??
If the hose I have is super flexible, and already has a small kink in it just sitting there, then when the engine is hot it would totally make that hose super flexible. Couldn't that absolutely prevent a pulse to the pump in the carbs?

So.. with that said, I'm going to finalize the fuel line replacements today and I'm going to take a piece of the strong fuel line I have and replace that flimsy pulse hose.

Depending on weather, I'm going to try this out today or tomorrow morning at 6am. I don't know if this is it, but it sure seems like this could be.

Thoughts from the gurus would be awesome!

Thanks!

 

[POPPS]

Well ,,,that hose normally is a preformed hose,,,hhmm…why did they change it out?,,,something for you to remove from your diagnostic equation

 

[mejim707]

Yeah I have no clue why they changed it. Maybe they broke the preformed one? Alls I know is after doing research, and finding people saying it needs to be reinforced and strong or it could collapse, I knew that this hose was wrong!

This is the hose they had in there. I just replaced it with 1/4 continental SAE J30R7 50 PSI fuel line.

Notice the kink at the top. I’m certain when this got hot it became really flexible and was closing off during vacuum.

 

[mejim707]

Still no dice. Engine starts perfect out of water, starts perfect in water but if I run it for a while, the shut it off for 15 minutes it will not start. If I wait 10 minutes it will starts but takes a little work to get it going but it does.

The entire fuel system was checked. All the old (not tempo lines) were changed. The fuel selector and pickup were inspected and good and clean.

The pulse hose was changed for a 50 PSI reinforced fuel line.

A few observations;
1. I still have air in the return lines. How?? Everything is sealed and I pressure tested the fuel system at 5PSI for 15 minutes with no leaks!

2. When stopped I clearly hear a dribbling sound as though water is dribbling into the exhaust. I can’t trace where it’s coming from. Is a dribbling sound normal while you just sit there at the dock? Could this be getting into the exhaust and bogging it down?

3. After trying to start it for a while the plugs are still dry. As though it’s not getting fuel when it sits.

4. I get home after a 10 minute drive and it fires right up.

5. Compression is 140 on both cylinders.

Does this point to the rotary valve? Did the rotary valve look bad in the pictures I posted?

Could the carb pump be bad? Maybe that’s what’s getting air in?

Can the fuel selector cut off fuel after sitting? As though the seal inside swells? Doesn't seem right.

 

[POPPS]

The carb is not electrical,,,so heat will not affect it,,did you try running the machine with the gas cap loose?…I keep leaning toward a coil getting hit and failing….or the rev clearance being too much,,,which will definitely produce your symptoms.

 

[mejim707]

Well, the saga continues.

I don’t think I’m getting fuel after I’ve run for a while and then shut it off. I try to start for 20 minutes and the plugs are dry. What can this be??

I rebuilt the mag again today because I am not getting fuel at all when it sits hot. The mag is perfect but I’m getting zero fuel. I used all genuine Mikuni parts and rebuilt The pump with all new gaskets and the pop off side again.

Maybe my pop off is too high at 35 PSI but apparently this is within spec.

I just ripped around then parked it at the dock for 15 minutes and it does not start.

I checked the shut off and I could blow air through it in its on and reserve modes. What Kinda shut off the Internet? Doesn’t seem likely.

Can the pulse stop working when the engine is hot? Even if I have 140 compression? I am at a total loss here. Any help would be greatly appreciated!

 

[mejim707]

The carb is not electrical,,,so heat will not affect it,,did you try running the machine with the gas cap loose?…I keep leaning toward a coil getting hit and failing….or the rev clearance being too much,,,which will definitely produce your symptoms.

Sorry pops I did not see your message before I posted mine.

So after trying to start it for about 20 minutes I checked the plugs and theyre completely dry. It is if I’m not getting any fuel. You think that the rave valves could be causing that if the clearance is off?

 

[POPPS]

Trust me,,,this has nothing to do with pop off,,,have you tried squirting fuel into the plug holes and see how it responds?

 

[mejim707]

Trust me,,,this has nothing to do with pop off,,,have you tried squirting fuel into the plug holes and see how it responds?

Thank you Popps! I really appreciate the help here!

I haven’t squirting fuel in the spark holes but I’ll bring a little squirt bottle with fuel next trip tomorrow morning.

Incidentally, my rave valves have the red center about 1/4 down from the level of the black cap. I just looted around and people are saying it should be level with the black cap.

Should I back them out and make them level and could that cause no fuel to enter the cylinders when the engine is hot?

I’m going to readjust them tonight per your direction. I’m still learning this engine but I’ll tell you I have this boat on point other than this hot starting issue. I live this thing and I feel like I’m so close to it being perfect I can taste it!

 

[POPPS]

Trust me,,,having raced 800’s for many many years,,,our screw head is even,,,normally,,,I screw them in…so they don’t back out,,,sounds silly,,.however,,,having the screw head level,,,helps it to not quite melt as fast if the motor overheats,,,ideally,,,you want to adjust them so they pop at the same time,,,
Throw fuel in there next time,,,and inform us,,,that should tell us a lot,,,if it’s fuel starvation,,,mechanical,,,RV clearance…or electrical…cdi,,or coil heating up and failing…

 

[mejim707]

Trust me,,,having raced 800’s for many many years,,,our screw head is even,,,normally,,,I screw them in…so they don’t back out,,,sounds silly,,.however,,,having the screw head level,,,helps it to not quite melt as fast if the motor overheats,,,ideally,,,you want to adjust them so they oth pop at the same time,,,
Throw fuel in there next time,,,and inform us,,,that should tell us a lot,,,if it’s fuel starvation,,,mechanical,,,RV clearance…or electrical…cdi,,or coil heating up and failing…

Ok I will bring fuel. It does try, and if I let it sit and then try it will kick but will not start and the plugs always remain dry brown.

I’m going to adjust the raves to be level tonight and bring a little bottle of fuel for tomorrow morning and report back!

Thank you!!

 

[mejim707]

Trust me,,,having raced 800’s for many many years,,,our screw head is even,,,normally,,,I screw them in…so they don’t back out,,,sounds silly,,.however,,,having the screw head level,,,helps it to not quite melt as fast if the motor overheats,,,ideally,,,you want to adjust them so they oth pop at the same time,,,
Throw fuel in there next time,,,and inform us,,,that should tell us a lot,,,if it’s fuel starvation,,,mechanical,,,RV clearance…or electrical…cdi,,or coil heating up and failing…

Popps, two quick things;
1. With these engines, if I'm getting fuel, shouldn't the plugs be saturated if I'm trying to turn it on for 20+ minutes? I could sit there for an hour trying and the plugs are dry as a bone. I'll post pictures below.

2. If I had a RV clearance issue, would the boat ever start in water? I can start it no problem in water when I just get to the lake. I drop it in, and regardless of how long it takes me to park the car and get back to the boat I can start it right up. Also I can start it up no problem if it only sits hot for a minute or two.

This issue only happens when the boat is hot, and sits for a while, ~15 minutes in water.

These are the plugs after 20+ minutes of trying to start it with full throttle open.
MAG Plug

PTO Plug

 

[mejim707]

Adding fuel did not work.

Rebuilding raves did not help starting, but really smoothed out running.

Starts perfect on water unless I run it on the lake then shut it off.

Adding fuel to the carbs, and cylinders did not help.

I bought an inline spark tester and I have strong spark on both cylinders.

If it was compression I don’t think it would start on water at all but it starts perfect when I get to the lake. And when I test cold both are about 140 PSI which is decent.

Does this point to the RV?

 

[POPPS]

Starting great cold,,,but not when hot can be rv clearance.

 

[mejim707]

Starting great cold,,,but not when hot can be rv clearance.

Ok, thank you! Then next stop I'll remove the carbs tonight and removed the RV cover to inspect.

Any tips would be awesome! I'll also search around for what to look for. I have no prob doing it, I'm just getting sick of making carb gaskets!! Other than that the job is easy.

Last thing, I hear water dribbling into my exhaust as it sits in water. Obviously the tail pipe is semi submerged but it sounds constant. I'll do some searching if others have the same thing.

 

[mejim707]

I don't own a micrometer, and I'm trying to see if anyone around here does. I do have solder however so I could open the cover, slap some solder on the top and bottom of the rotary valve, then put the cover back on and torque it down to 20Nm / 15 pound feet. This should squish the solder and maybe this will be accurate.

I don't know, I'm totally new to this so I'm flying blind for the most part. But whatever, I'm just going to dive in and pull the carbs and get this cover off.

 

[mejim707]

Continuing the restoration. I’m not doing this just for fun, I’m doing it because this boat was neglected and left under a tree to rot. It deserves this and man, I love it!

I pulled the RV. Not a bad job, pretty easy. However the bolts seem very short and one was barely even in there!

These are the parts and they don’t look bad? It looks like they were machined at one point. I dunno.

I’m going to get the clearance measurement and if it’s out I’m just sending them to SBT for the core first replacement since they can’t find my number in their category. I have 6811 300.

The cover is mostly smooth. The valve is as well with a slight Nick on it.

I also marked it with an out line and the top was marked as reference. I marked the gear tooth and matched to the valve and block. I’m not screwing with timing as well lol

 

[mejim707]

The bolts holding the cover on are about 1/4 too short. The cover was barely holding on there. Plus there was a significant amount of build up around the edges on the block and cover. I got new bolts from a local shop and I'm going to fully clean the mating surface on the case. I'm going to do the solder method shortly.

I contacted SBT and they said it would take 15 days to get another cover and valve if I needed it! And that's after I have to ship them mine, then two days at least to process my cover then 15 days from then before they ship it back. So it'll be like 20+ days before I could get my boat running again and they offer no expedited replacement.

So, does anyone have a recommendation on where I could get a new cover and valve from a trusted source where I don't have to wait over 20 days t get it?

I'm sure someone here has advice on where I could get a good replacement that's already in spec please!

Thanks!

 

[mejim707]

Welp, I got the measurement. The crushed solder is .0125 and the valve is exactly .024. That gives me .0115 for my clearance totally in spec.

However!!! I need help!!!

The previous owner stripped the lower left bolt hole for the cover! Don’t tell me I need a new block and this is why I’m having the troubles. The old bolts were far too short and I use the correct size and it does not tighten. Unreal.

What are my options please and thank you!

 

[mejim707]

Well, I got the bolt in, and it's tight but not down to 15 pounds. I got it close and did not use the lock washer. Instead I used the blue loctite 242 generously on the threads then drove it in. I stuck a feeler in the hole to get the total depth to make sure I wouldn't penetrate the block without using the lock washer. It's only about 1/16th of an inch for the lock washer but I didn't want to take a chance.

The other 4 bolts are in and torqued to 15 pounds. It's just that one that's about 12.

The clearance is still good on the valve. I have a feeler gauge and was able to barely get the .011 in. The solder crushed to 0.125 so I couldn't even get the .012 feeler gauge in because the .012 feeler is closer to .0128 when I used the caliper on it.

I'm pretty confident the rotary valve is perfect. I just have concerns about that 1 bolt. And this explains a lot.

I know I'm talking a lot on this thread, but I'm just documenting my work. And this is the first thing I've run into that gives me that sick feeling and I need some advice please.

Thank you in advance.

 

[DarrenR]

Hey Mejim,
I've been following the post to see what works so I appreciate your thorough documentation. I am wondering if there is anything else you can do to be sure fuel is feeding via the pump and filter. Maybe just try bypassing the fuel filter in case it's leaking air? I'm going to install my new fuel filters today but I won't get a chance to water test it. I am having the problem with both my engines so maybe that points to a problem that would effect both like the fuel tank. Did you ever try starting with the gas cap loose or off incase there is a slight vacuum on the tank? I suppose that could happen if the tank was warm then cooled slightly and vapors condensed back to liquid causing vacuum on the tank or other parts holding fuel.
Out of curiosity, what part of the country are you from?

 

[mejim707]

Hey Mejim,
I've been following the post to see what works so I appreciate your thorough documentation. I am wondering if there is anything else you can do to be sure fuel is feeding via the pump and filter. Maybe just try bypassing the fuel filter in case it's leaking air? I'm going to install my new fuel filters today but I won't get a chance to water test it. I am having the problem with both my engines so maybe that points to a problem that would effect both like the fuel tank. Did you ever try starting with the gas cap loose or off incase there is a slight vacuum on the tank? I suppose that could happen if the tank was warm then cooled slightly and vapors condensed back to liquid causing vacuum on the tank or other parts holding fuel.
Out of curiosity, what part of the country are you from?

Yeah it's an adventure lol I'm located in the north east and never use this in salt water. Only fresh lakes.

FUEL SYSTEM VALVE
So the 96 challenger doesn't actually build pressure in the tank. The two way valve on the side of the hull is a free flowing valve with only a screen, and with its design and the loop in the hose it prevents water form getting into the tank. I was thinking the valve could be plugged and holding pressure but I never heard air relieve from the system when I removed the cap. So I checked the valve and sure enough, it's has no restrictions on these boats.

FUEL FILTER
I haven't bypassed the fuel filter. The filter is a brand new OEM unit and the boat starts in water with no issue when it's cold, and runs amazing with no fuel troubles. Plus the plugs are the nice dry brown you'd want. If it was fuel starvation the plugs would be white and look burned. So I'm pretty confident the fuel system is good.

MAG PUMP
I also rebuilt the MAG carb pump with genuine Mikuni parts and replaced the flimsy pulse hose with the reinforced fuel line.

PRESSURE TEST
I also pressure tested the fuel system to make sure there were no leaks. I filled the tank to the top, removed the relief valve from the side of the hull, and used that hose, with my hand pump to pump no more than 5 PSI of pressure into the tank. You do this then wait to make sure it holds for 10 - 15 minutes. I waited 15 and there were no leaks.

OTHER
I also purchased an inline spark plug tester and I have proper spark on both wires. I also added fuel directly to the carbs and cylinders but that did not help either.

ROTARY VALVE
So, with all those things out of the way, and my compression being 140 PSI in both cylinders, as POPPS brought out that pointed me to the RV.

Before I removed the RV cover, the valve inside seemed to have a bit of play. Not good. As it turns out, the outer edge of the cover, and the mating surface on the block had a bunch of crap on them preventing them form mating flush. Even if this is only a few thousands of gap, that will throw off the clearance enough to prevent starting in water.

The previous "mechanic" / owner used bolts that were almost 1/4" too short, and one of the holes was stripped out. Between a striped bolt, the crap on the mating surfaces, and the inability to torque the bolts because they were too short, all of these add up to a faulty RV install.

When I cleaned the RV, added two half inch pieces of solder on the upper and lower sides of the face of the valve (with a little grease to hold the solder) and torqued the 3 bolts down to 15 pounds, and the forth to 12 pounds, the solder squished and when measured it's at .0125 on the money!

This leads me to think when I fix the bolt hole, and get it back together the RV will be perfect and my starting issues must vanish after this since the RV, cover, and block are all at the correct clearance.

 

[DarrenR]

Sounds like a plan. If it works maybe I'll tread down that path myself. I was hoping for an easier fix though. Good luck

 

[mejim707]

Sounds like a plan. If it works maybe I'll tread down that path myself. I was hoping for an easier fix though. Good luck

Thanks I'll keep you posted.

But to be honest, this is easy. You can remove both carbs in one shot without removing the cables. Just the carbs, pulse line and I removed the returns. I put both carbs in a plastic bag and rested them in the hull.

Pulling off the cover and valve was easy. You just need to be sure you mark the valve before taking it out so you can get it back in there without having to mess with timing. I marked it using sharpie, and also marked the top of the valve to make sure I knew what side was out.

Other than that, a good quality digital caliper is key and you'll have no trouble testing clearance.

I'll keep you posted and I'll assist if you need help figuring out how to check clearance if you get to that point.

 

[mejim707]

Welp I’m at a loss. I’m getting great spark. The RV is in spec at .0125. The compression is 140 each cylinder. It will not start when warm on water!!! It starts perfect in water when I get to the dock. It will not start after running.

I hear water coming into the exhaust pipe. And there are bubbles in the fuel return line with seemingly no way to enter and they do not move when I try to start.

The bubbles do not move when I try to start. The pulse line is perfect and the boat runs spectacular otherwise.

I’m really at a loss here. What else can this be??