Perplexed..175 Johnson Starting Problem??

[jnl911]

I hope there are some experts on these motors of the 1993 60 deg v6 optical vintage out there.....

This motor runs great after I get it started. But there lies the problem. Unless I squirt something into the the carbs... it will not start. I have used wd 40 or premix. Very strange, I have replaced the optical sensor, power pack, have new plugs, wires and have done the troubleshooting in the manual until I'm blue in the face.

I pull the two small hoses off from the cold start valve where they enter the manifold.... after pumping the bulb and pressing in on the key, they squirt with good pressure. What I really don't understand is that when I put a hand vacuum pump on the orafices that connect the hoses to the manifold, they hold some vacuum. I have tried putting compressed air on them and there seem to be significant back pressure. How does the fuel get into the manifold? Both sides react the same.....

From what I have read, the cold start valve supplies extra fuel directly into the manifold. Seems to me that it should be a straight shot. I am thinking that there is something wrong here. The previous owner put a new power head on the motor..... could it be that the manifold gaskets are the wrong ones and have no relief for the cold start circuit?

I am new to outboards, however I have been building auto racing engines for 20 years.... but I may still be overlooking the obvious...Anyone out there with some grey hair who can help me with this?

Thanks in advance

 

[Rscardina]

Re: Perplexed..175 Johnson Starting Problem??

do you have a choke or push in key choke? I dont know your motor 100% but it it is a push to choke then you should have a primer solenoid.

at cold starts you are to turn and push the key in while cranking, after you have primed the bulb of course.

what this does is bypasses carbs and shoots fuel directly to the heads helping it start from cold. the push to choke is a momentary thing, meaning once you release the key it shuts off.

 

[Rscardina]

Re: Perplexed..175 Johnson Starting Problem??

I pull the two small hoses off from the cold start valve where they enter the manifold.... after pumping the bulb and pressing in on the key, they squirt with good pressure. What I really don't understand is that when I put a hand vacuum pump on the orafices that connect the hoses to the manifold, they hold some vacuum. I have tried putting compressed air on them and there seem to be significant back pressure. How does the fuel get into the manifold? Both sides react the same.....

the hoses that come off the choke solenoid split into two and then 4 and so on depending on the amount of cyliders you have. Each one feeds a cylinder.

are you saying you cant get air or fuel past these points?

 

[d.boat]

Re: Perplexed..175 Johnson Starting Problem??

From your post, I really can't understand exactly what your starting procedure is since you didn't mention it, only the fixes you were trying. Maybe we should backtrack to that, but excuse me if this is already a given for you. But maybe not if you're new to outboards.

1 Pump bulb until firm - this fills carb. bowls.
2 Lift cold start lever (sometimes not required if cold start feature is working)
3 Turn key to "on" , but not to "start"
4 Push in key to prime cylinders. It is not a choke as some call it, but a primer - this moves the fuel up from carb bowls to cylinders
5 Hold the prime for a few seconds (sometimes as little as 1-2, sometimes as many as 10, you have to figure this out for your engine)
6 Release key/primer and start engine. Sometimes need to bump the key/primer to keep it running until warm.

If you're already doing this and it's not working, then there is probably something you need to track down like you have described.... but I don't have the expertise to advise on that.

 

[Rscardina]

Re: Perplexed..175 Johnson Starting Problem??

"
4 Push in key to prime cylinders. It is not a choke as some call it, but a primer - this moves the fuel up from carb bowls to cylinders
.

dboat..i believe the primer solenoid, at least on my boat, bypasses carb bowls all together. they are seperate hoses from the fuel manifold, I am pretty sure that is the case for all of them, however I wont say for sure since i dont know this guys motor.

sounds like something is plugged or operator error..

 

[jnl911]

Re: Perplexed..175 Johnson Starting Problem??

Maybe I should try this again.... I guess I left out some relevant details. The motor definitely has a primer solenoid and it works in so far as getting the extra fuel to the orafice on the intake manifold (the little copper nipple), I have tested this. It is getting sufficient spark (blue at 11mm on tester), when I start, I am pumping the bulb, it is firm, turn key to one click, push in for 8 seconds, solenoid is opening, crank... I know the drill. But it does not start.

Problem is I do not think that the fuel from the cold start solenoid is getting into the manifold. After I crank it a few times my plugs are not wet. When I put vacuum or air pressure on the copper nipple there is resistance. If there is that much resistance, the pressure from pumping of the bulb certainly could not overcome it. There is one fuel inlet from the solenoid on each cylinder bank that must branch via the manifold to all the cylinders.....

My question is... for anyone who has pulled the carbs and manifold off of one of these beasts, does the routing for the fuel to get to the manifold from the cold start supply go through the rubber manifold gasket? Could an incorrect gasket be blocking the passage way?

I guess I need to pull the carbs and manifold. There is definitely blockage getting the fuel into the manifold.....

 

[d.boat]

Re: Perplexed..175 Johnson Starting Problem??

dboat..i believe the primer solenoid, at least on my boat, bypasses carb bowls all together. they are seperate hoses from the fuel manifold, I am pretty sure that is the case for all of them, however I wont say for sure since i dont know this guys motor.

sounds like something is plugged or operator error..

I'll have to admit I really don't know and am probably guilty of mistaken info. That's the way a mechanic explained it to me about a hard starting early 80s V6 I once had, so it's the way I've always visualized it. SORRY all.

 

[Rscardina]

Re: Perplexed..175 Johnson Starting Problem??

Maybe I should try this again.... I guess I left out some relevant details. The motor definitely has a primer solenoid and it works in so far as getting the extra fuel to the orafice on the intake manifold (the little copper nipple), I have tested this. It is getting sufficient spark (blue at 11mm on tester), when I start, I am pumping the bulb, it is firm, turn key to one click, push in for 8 seconds, solenoid is opening, crank... I know the drill. But it does not start.

Problem is I do not think that the fuel from the cold start solenoid is getting into the manifold. After I crank it a few times my plugs are not wet. When I put vacuum or air pressure on the copper nipple there is resistance. If there is that much resistance, the pressure from pumping of the bulb certainly could not overcome it. There is one fuel inlet from the solenoid on each cylinder bank that must branch via the manifold to all the cylinders.....

My question is... for anyone who has pulled the carbs and manifold off of one of these beasts, does the routing for the fuel to get to the manifold from the cold start supply go through the rubber manifold gasket? Could an incorrect gasket be blocking the passage way?

I guess I need to pull the carbs and manifold. There is definitely blockage getting the fuel into the manifold.....

I've heard of some folks using WD40..or a syringe with a small diameter tube (same size as the ones that are suppossed to workin) and ..fill syringe with alcohol or pre mix.. and inject.. it should pass..if not its definitely restricted

on mine..the primer solenoid is fed by the fuel manifold.. then each finger feeds individual carbs. the solenoid out comes off in two tubes then splits..so when injecting pick a point after the split..as i assume you have done with air already.. I do not believe those brass fitting are check valves..but I am not 100 sure

 

[jonesg]

Re: Perplexed..175 Johnson Starting Problem??

I have a 1994 optical V6, when the engine is running, pushing the choke will kill it by flooding in less than 3 seconds, so yeh you have a restriction.
Bad gasket sounds reasonable.
You can pull the fuel line from the choke and see if it spurts when choked.
Rebuild kits for the choke are $12 here on iBoats if it is leaking.

 

[jnl911]

Re: Perplexed..175 Johnson Starting Problem??

Thanks Guys,

You have reconfirmed my thoughts. When I engage the cold start enrichment while running, there is no effect. Definitely a restriction beyond the manifold.

I was just trying to avoid pulling the carbs and manifold. I'm a lazy old fart with grey hair and I don't really need the aggreviation. But such is life.

Thanks again, if anyone needs help with Porsche 911 or BMW engines, give me a shout.

J.