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Difficulty starting and higher RPM's than normal |
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Travis Eacret 
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Joined: April-23-2020 Location: Indianapolis Status: Offline Points: 23 |
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 Topic: Difficulty starting and higher RPM's than normalPosted: June-22-2020 at 1:54am |
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Forgive me if someone has been through this before but I am looking for solutions to an engine that is difficult to start cold or warm. Once it starts it sounds like it runs fine but the last time out on the lake the RPM's were higher than normal at any given speed. I have not made any changes to the prop so could anything else cause the engine to run higher RPM's under load? I have a PCM model PLP (351 with a Holly carburetor) on a 1995 Sport Nautique. Could the starting problem be related to the RPM problem? I just replaced the spark plugs this season but it's the second time they have been replaced in the 120 or so hours I have used it since purchasing the boat.
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1995 Sport Nautique
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Mpost
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Joined: July-05-2018 Location: Monticello, MN Status: Offline Points: 323 |
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Posted: June-22-2020 at 10:28am |
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Can you give a description of what you mean by hard to start? What do you have to do to get it started? Pump the throttle several times? Open throttle while cranking starter???? This will help tell what might be causing your hard starts.
Did your high RPMs issue the last time out really sound like higher RPMs or was it possibley just the tach not being accurate. Look at this link to a recent post. link |
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84 SN Sold 98 SN Lund Pro V 1975 Alumacraft
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Travis Eacret
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Joined: April-23-2020 Location: Indianapolis Status: Offline Points: 23 |
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Posted: June-22-2020 at 10:42am |
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Thanks for the link on the RPM issue, I suspected that it might have to do with the gauge as it went from running on the high side to normal and back to running high in the same day. the motor sounded fine to me.
to get it started when cold I pump the throttle a couple of times and then open a little while cranking the starter. I usually have to do this a few times to get it fired up and then once it does fire up rev up the engine a little for a few seconds to get it to stay started. In the past once it was warm it would start just by cranking the starter but the last time out after the initial start it struggled to maintain a consistent idle, this when away after the engine warmed up but every time we tried to start it warm it would just crank, so tried opening up the throttle and it still took a little cranking and a few tries to get it going. I try not to crank it too long on any given attempt. |
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1995 Sport Nautique
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Travis Eacret
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Joined: April-23-2020 Location: Indianapolis Status: Offline Points: 23 |
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Posted: June-22-2020 at 1:22pm |
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I also failed to mention that occasionally a puff of smoke comes out of the carb after a couple of rounds of trying to start it.
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1995 Sport Nautique
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GottaSki
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Joined: April-21-2005 Location: NE CT Status: Offline Points: 3327 |
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Posted: June-22-2020 at 1:35pm |
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Thinking your smaller distributor weight spring has snapped
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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Travis Eacret
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Posted: June-22-2020 at 2:42pm |
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Distributer looks fairly new and I checked the timing, however not under load, it was correct at idle and seemed to progress just fine when revving the engine up.
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1995 Sport Nautique
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Travis Eacret
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Joined: April-23-2020 Location: Indianapolis Status: Offline Points: 23 |
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Posted: June-22-2020 at 7:32pm |
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Adjusted the dial on the RPM gauge like described in the linked post. Then I looked under the distributer cap just to see what if anything seemed wrong and I found that the gasket still had the backing paper on it which had started to come out from the gasket and was just dangling down where the rotor spins. I pulled that out, reset the gasket and put the cap back on. double checked that my spark plugs looked good and the wiring matched the firing order then tried starting it in the driveway pumping water from a bucket. It fired right up and idled fine. I waited until the engine warmed up then opened the throttle and is sounded beautiful. Shut it off and tried starting warm and it fired up no problem and no pre pumping the throttle or opening it while starting.
Could the loose paper backing to the distributer gasket be causing a misfire issue making starting difficult? I'm anxious to get the boat on water to see how the engine reacts to being under load. |
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1995 Sport Nautique
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Travis Eacret
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Posted: November-16-2020 at 9:01pm |
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So following this post the hard starting issues resumed. I went through the remainder of the season dealing with them and lately have been trying to solve the problem. It seems like the carb is getting flooded but I could be wrong. Just a reminder I have a '95 Sport Nautique with a Holley carb on a 351 PCM with GT heads. Here is how a start goes...when cold I given it a couple pumps of the throttle and crank it, turns over strong but usually nothing or maybe a cough out the carb as I release the key. I try to give it just a little gas while cranking and listen for any sign of it firing up. After the first time I don't prime the carb just give it a little gas while trying to start it. Once it fires up and the choke opens up it idles and runs well. If I shut it down for a few minutes to change a skier or wakeboarder out then we have difficulty starting again. I always try to crank it without priming but when it doesn't fire up I usually give it a couple of small squirts, then I'll get a big cough out of the carb complete with smoke and sometimes fuel spray) then it eventually fires up again. Another unusual thing is it seems to catch most of the time right as I am releasing the key.
Since then I have rebuilt the carb and adjusted the curb idle screw, idle mixture screws and the accelerator pump bolt to the specs I've found on the internet or from Holley. Even purchased a vacuum gauge to make sure I'm doing it right. The highest reading I could get was about 16 in Hg. The vacuum gage shows that right on the line between normal (green) and late ign. timing (red). So I thought I'll check the timing and it was right on 10 deg. BTDC. I tried advancing and retarding the timing a couple of degrees each way and it made no difference. I also put new spark plugs in as the ones I put in at the beginning of the season looked carbon fouled. Finally I did a resistance test on the ignition coil and spark plug wires and everything seemed good according to my research. So I have spark, possibly too much fuel, and maybe to little air? Please help me diagnose this issue as I am afraid I might be making things worse just letting it go.
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1995 Sport Nautique
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63 Skier
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Joined: October-06-2006 Location: Concord, NH Status: Offline Points: 4232 |
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Posted: November-16-2020 at 10:43pm |
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A few things come to mind. I know you inspected your distributor and found the paper, but not sure you ever took a look at your advance mechanism to make sure springs are ok (as suggested above) and it's operating correctly. When running, does it run up to WOT with no hesitation? Feels like it has the power it should? Not sure what you have for a timing light but one with advance would tell you more about how it's running. Did you inspect the fuel line and anti-siphon valve at the tank? It would be good to get a fuel pressure gauge and see if you have adequate fuel pressure when cranking and running.
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'63 American Skier - '98 Sport Nautique
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GottaSki
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Joined: April-21-2005 Location: NE CT Status: Offline Points: 3327 |
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Posted: November-17-2020 at 8:08am |
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huh...Pumping the throttle on a warm engine is just not how these start. Maybe it worked for you once and reinforced a flawed technique. Its likely flooding out when stopped then more pumps don't help, hence the smoke, pops and farts
Just crack the throttle a little a leave it there till it fires to clear it out. Vacuum seems a bit low. that needs to be investigated. Also set idle mix for max vacuum under load in forward gear, else if done at neutral it will be weak in gear, hard to restart after a quick shutdown, the delta-rpm between neutral and forward will be frustratingly high, anad will not launch hard and sometimes stall when you punch it. The starting when releasing the key needs to be addressed. Cables and connections cleaned for diagnosis, unplug the choke for a restart, that will raise the energy available to the ignition. if improved, there is too much voltage drop on the old wires. Also, what sort of battery is in the boat? |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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Travis Eacret
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Posted: November-18-2020 at 7:57pm |
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Thanks for the feedback, I may not have a chance to look at things again until Monday at least. I'll get back report what I find then.
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1995 Sport Nautique
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SNobsessed
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Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Posted: November-20-2020 at 8:12am |
Is there any way it could be mis-wiried such that there is no power to coil while cranking, but power when key is at on position?
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“Beer is proof that God loves us and wants us to be happy.”
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Travis Eacret
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Joined: April-23-2020 Location: Indianapolis Status: Offline Points: 23 |
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Posted: November-29-2020 at 12:32am |
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I think I solved the problem. My battery is a lead acid with 850 CCA and 150 Reserve Capacity.
So thinking this was an electrical problem I started testing voltage from the battery and following the cables on up to the helm; I didn't find any significant voltage drop (over 10%) until I got to the 3 way ignition switch and I was losing like 50% of the voltage. Starter was ok, solenoid was ok, and unplugged any connections I found prior to the helm. Checked impedance on the ignition switch on the dash and the 3 way ignition switch and they seemed ok. I looked at most of the electrical connections under the instrument panel and nothing seemed loose however I still unplugged quite a few and plugged them back in including the horn which previously would only work if the motor was running. There must have been something causing voltage drop under the instrument panel because today I put things back together and had over about 12.6 volts on the 3 way ignition. I tested the engine in the drive running in neutral and it started right away cold just needing a few extra RPM's to get warmed up, and also started instantly after warmed up with no pumping of the throttle and it didn't matter if I let it sit a few minutes or not. I also found a place to connect the vacuum gauge directly to the manifold and was able to get a reading of about 18 Hg at just under 700 RPM's. I also verified the timing was still at 10 deg BTDC. I understand that I should make adjustments in gear under load but I could not do that today and I just took the opportunity to winterize the boat while I had it out since the forecast calls for multiple nights below freezing. I know I wrote a book but typing out my problems and thinking through the symptoms a little slower along with suggestions from the forum helped my get my boat running. Thanks and Happy Holidays
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1995 Sport Nautique
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8122pbrainard
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Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Posted: November-29-2020 at 5:27am |
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Travis,
Good job. Even though you didn't find the exact problem spot, glad you were able to correct the hard start. Bad connections typically due to corrosion in the moist marine environment are pretty commen. Besides connections, contacts inside switches can also cause problem. If the problem comes up again, I'd suggest going back to the connections cleaning them and then use some dielectric grease when reassembling. I'd also take a closer look at the ignition switch with the VOM. You should get a near zero resistence reading across the contacts.
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Travis Eacret wrote: