Starting Problem Johnson 175

dajohnson53 · Jun 15, 2004

I would appreciate any insight or words of wisdom. This is an older V6 carb'd engine (1982) but "remanufactured" in the mid 90s. I have an in-line bowl type water separating filter which I empty regularly as well as a normal little white in-line filter inside the cowling near the fuel pump. I put the engine up each fall with topped off tanks with fuel stabilizer in the tanks and run through the system. It can be very difficult to start when cold. It starts easily when warm. It idles very smoothly at around 7-800 rpm when warm (1200 or so when cold) and runs smoothly through the rpms to WOT at approximately 5500. I am very happy with the performance once started. My cold starting procedure. after checking fuel and air vent is to: 1 pump bulb until firm. 2 lift the cold start lever fully 3 turn key to on (not start) 4 press key to prime carbs - hold for approximately 5 seconds (I can hear the switch inside the cowling when I press the key) 6 attempt to start engine. What happens is that the engine fires once (only once) and disengages the starter - at which point, I of course immediately release the key. It will do this time, after time, after time for several minutes. Seriously - this will happen many, many times for more than 5 minutes. One fire, starter disengaged. I have a strong battery and haven't had any problems (yet) with the battery running down before I eventually get it started. I vaguely recall occasionally having this problem iintermittently in past seasons, but never to the extent of considering it an issue. Eventually it always starts, but it does this one fire and out deal for a frustratingly long time. Once I get it started, I can shut down right away, before it's really very warm, and it will start right up again. If it cools down again, I have to go through the same routine. It always starts easily when warm. I have tried priming more and less - with no discernable effect. I have tried cold start lever up and down as well. This engine has an aftermarket jet lower unit. This means that there's no true "neutral". It's always pumping water and thus has a load, even at idle. It *seems* - but is hard to verify - that if I raise the engine to just where it pumps water, thus reducing the load a little bit, that seems to help. This is a vauge feeling on my part because it definitely doesn't make a night and day difference. The plugs look good to me but I'm no expert. But I haven't actually changed them (which is what I'm going to try next). I also haven't tried starting it on the hose to see if that makes a difference vs. starting it in the water. There is much less load while on the hose because the jet pump is not really pushing any water at all. I'm going to try this as well.

OBJ · Jun 15, 2004

Re: Starting Problem Johnson 175

Hey D. What it sounds like is, you may not be getting fuel through the primer solenoid. Have you tried flipping the manual prime lever to manual on the primer solenoid? You can also pull the primer hose from the top carb and put it in a jar. Have some one crank the engine while holding the key in to "choke". If there is gas spurting from the hose, then all should be well. If not, check the fuel hose to the primer for any pluggage. It really dosen't do any good to hold the key in for a few seconds before cranking. Just turn the key to on, push in and go to start.... Keep us posted.

dajohnson53 · Jun 28, 2004

Re: Starting Problem Johnson 175

Sorry for so long in following up on this OBJ. The sad but common story of not enough time for boating. I didn't specifically trouble shoot the primer solenoid like you recommended - didn't have help yet to do the hose in the jar thing. But I did run the motor a couple of times recently and wonder if the following makes any sense at all: Do you think that excessive back pressure could make it harder to start, and if so why? This engine has a jet lower unit. Last time I ran the engine, it started much easier - just a couple of trys (as opposed to the 10 minute ordeal of the past). What was different? The boat was on the hose in the driveway. This provides much less back pressure on any engine, prop or jet, but I think that it's much more pronounced with a jet unit. The reason: A jet unit is always "in gear" - the drive impellor is always engaged. Neutral is just a fine adjustment of the reverse boot (which cups the jet outlet and re-directs the jet flow to push backward rather than forward - very similar to the reversing mechanism you see on some jet aircraft). This neutral position directs the flow both forward and rearward, thus "neutral". It is not a true neutral in the sense of no power to the prop. Therefore, while in the water, there is as much resistence against the engine as there would be on a normal prop outboard if it was in gear. So, armed with the anecdotal evidence that the engine started easier on the hose, and thinking "hmm, backpressure??", the next time (and only time since my original post) I put it in the water, I raised the engine with the hydraulic jack as high as it would go and still get water pressure (read on my pressure gauge). With a jet, this is with the jet intake barely in the water, and actually almost cavitating (passing tiny wakes caused cavitation). Again, the engine seemed to start relatively easily - just a couple of tries instead of the ordeal. I also held the key in priming position for a good 10 seconds (previous routine was about 5 - 7). Therefore there are two factors I'd like to follow up to test - the length of the priming needed (e.g. is 10 seconds really better than 5?) and also the idea that the motor must be raised as high as possible for easy starting. The problem with testing this "scientifically" is that the problem occurs only when the engine is dead cold - so this is really only a once per day issue. Once it starts just once, it is easy to start thereafter. Therefore, I can only test one theory per outing and my outings are sadly too few and far between. Coupled with that is the fact that I almost always boat with the wife and kids and therefore am HIGHLY motivated to get it to start right away rather than experiment. Thus, I'm sure I'll be way too tempted to try BOTH techniques (long priming and high engine). I will be testing the theories though and will report back. In the mean time, anyone have any ideas as to the role of back pressure in this situation? Thanks again for any help you can give.

cvx35 · Jun 28, 2004

Re: Starting Problem Johnson 175

hold key in while cranking... pushing key in opens primer...no fuel will go into intake unless engine is cranking, while creating crankcase pressure to pull fuel into intake.

Dhadley · Jun 28, 2004

Re: Starting Problem Johnson 175

Fuel will go into the intake without the motor turning over. The primer is simply a valve. Once pressure is built in the system by pumping the bulb and you open the valve (push the key in while in the On position) fuel will enter the motor until the pressure drops. Each motor may be a bit different. Some will start after holding the key in for a count of 5. Some 8. Some may be 10 but most of the fuel is already released after about 5 anyway. What spark plugs are you using? Are you still using last years fuel or is it fresh? What grade?

clanton · Jun 28, 2004

Re: Starting Problem Johnson 175

Clean the primer hose nipples on the carb and enlarge .010.

dajohnson53 · Jun 28, 2004

Re: Starting Problem Johnson 175

Thanks - that helps me understand exactly what the primer does, and how the key-soleniod switch relates to the manual lever/valve. I burned 40 - 50 gallons of last year's fuel - but it was fresh last fall when I put the engine up for the winter and I used Stabil stabilizer. I'm now using fresh fuel. I use 90 octane (because my mechanic says to). The plugs are Champion QL77JC4 (828M) gapped at 30 and are in like new condition - no fouling evident in any cylinder. As I might have mentioned earlier, when the key is in the ON position, but not started, and I push the key, I can hear a clicking sound from the engine. But I haven't actually tested the primer solenoid/valve functioning yet. Once it gets over the initial problem and starts, even if if shut down right away, and not warm yet, it will then fire right up just like a well tuned FI car engine and really idles better than it ever has (see below). The most recent change was that this spring, my mechanic, while troubleshooting a bad sneeezing/rough idle, found a defective plug in one of the disconnected pars of the disconnected VRO fuel pump - causing a major air leak I guess. He re-plugged it and the idle has been truely sweet ever since. But the starting "seems" to be more difficult than last year. I say "seems" because being an old carb'ed V6, it's always been a little tricky to start (really, just a little; no worse than my 86 Chevy on a cold day), but this has been a real problem lately which I really don't remember having. I'm trying to figure it out myself because this time of year it will be a while before my mechanic can take a look at it. Thanks again.

dajohnson53 · Jun 28, 2004

Re: Starting Problem Johnson 175

Originally posted by clanton: Clean the primer hose nipples on the carb and enlarge .010.

Thanks. I (hope) to check out the primer functioning one of these evenings and will clean out while doing so.

dajohnson53 · Jul 20, 2004

Re: Starting Problem Johnson 175

I just wanted to follow up on this and tell you what I found. First, the VERY unfortunate fact is that I have not used the boat much in July. Oh, I've been having fun, but just not in the boat. I also haven't actually visually tested the functioning of the primer, but I believe it does work, at least adequately, based on the below. Last couple of times I started the engine, it started acceptably well. I did two things differently so can't really say which is more important, but I suspect both are. As you recall, this is a jet unit which is always spinning the drive impeller, even in neutral. Therefore, there seems to be more load on the engine when starting than a prop drive in neutral. When I back the boat into the water to attempt to start the engine before unloading, the stern of the boat and the motor tended to sit very deep in the water, much deeper than normal jet operating depth. I believe this caused increased load. I can lift the lower unit virtually out of the water with this jet - the intake is on the very bottom of the drive. Height at idle is only limited by water pressure as indicated by the gauge and/or telltale. This much higher position "sounds" like a lot less load than when the jet unit is sunk very deep. So, last time I started the engine at a height as high as possible and still get water circulation. The other thing I did was to prime more aggesssively. I'd been priming for only about 5 seconds. I think I was worried that I'd been flooding it. Now I prime for a full count of 8-10 seconds when it's cold. With the new routine, I've only had to do this twice before it started, so I don't know what I'll do re: priming if it is more baulky than that. Between the two above factors, the engine started much better - within just a couple tries vs. the old routine of many, many minutes of trying. Of course, it doesn't start up care free and snappy like my FI cars, but it fires and sputters enough to coax on to full life with the primer for the few seconds it takes to really idle OK. Before it was one fire and out, no chance for coaxing. My theory is that I just wasn't priming it enough at first. I also feel that by raising the engine as far as possible, it decreased resistance at cold start, thereby letting the initital less than perfect, sputtering firing to keep it turning enough to catch on. In my experience, this is pretty normal and really OK for an old carb'd 2 stroke. I'll experiment a little more, but now I'm happy to find a routine that seems to work.

Dhadley · Jul 20, 2004

Re: Starting Problem Johnson 175

Less mid section in the water = less back pressure. Makes perfect sense. Thanks for the update!

dajohnson53 · Jul 20, 2004

Re: Starting Problem Johnson 175

By the way, thanks to all of you for the info and advice. 'preciate it.

dajohnson53 · Aug 21, 2004

Re: Starting Problem Johnson 175

"The final word" OK, I've been able to run the motor a few times in the past month! I've settled on a starting routine that has solved my problem and I just wanted to report back to all of you that gave me advice. First, while I think the back pressure issue might have had a little to do with it, I think it's a minor factor and not the cause of the problem. I modified the starting procedure in two minor ways and it made a large differnce it appears. 1 - I now pump up the bulb until it's as hard as I can get it. Not just firm, but keep pumping it until I pretty much can't pump it any more. 2 - I prime it (key in on position,key pushed in) for a long "10 second" count. Not a quick 8 second count, but a very patient "one-onethousand... ten-onethousand" kind of deal. I figure given my impatience, this is probably 8 or 9 seconds. If I do an 8 second count (probably more like 5 or 6 seconds) it makes a remarkably large difference - it just won't start easily. So "Ten" it is. The motor now starts right up - even impressed my wife who has always disparaged the big white beast. Thanks again to all of you for your comments and advice.

Solittle · Aug 22, 2004

Re: Starting Problem Johnson 175

We just need to find out what makes these motors happy.

dajohnson53 · Aug 23, 2004

Re: Starting Problem Johnson 175

No kidding - turns out that along with the above, I need to pat it gently and say sweet things. If I start cursing (often tempted!), it's all over.

Starting Problem Johnson 175

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