RPM gauge reading double RPM???

[KRS]

Hello all.<br /><br />Started my boat today, after a shot of Thrust, and noticed something that seemed okay last year.<br /><br />My boat's OEM RPM gauge appears to be reading double the actual idle. At what I think is normal idle of 1300-1500 (yes it idles high) my gauge is reading 2600-3000, then some throttle makes it peg when I estimate it at 3200 or so.<br /><br />Any thoughts, about this post???

 

[allen.st]

Re: RPM gauge reading double RPM???

I too have this problem, have you tried hooking up a different tac to verify that yours is not working properly? I used 2 different styles, 1 just hooked to the coil and the other reads the spark on #1 plug wire. I would try this first, then check the back of the tac and see if it is still set correctly as a lot of them work on different number of cylinders, 2, 4, 6 or 8. If it is not reading properly I need help there too I have not gotten that far yet.

 

[Don S]

Re: RPM gauge reading double RPM???

On the back of the tach is a switch that may have gotten moved. Look at the back of the tach, it may be set for 4C instead of 8C.<br /><br />If Thrust is starting fluid, aka ether, get it off the boat. If you have to use that to start your engine, then you need some mechanical work before you destroy it.

 

[KRS]

Re: RPM gauge reading double RPM???

I will check the switch, I was messing around behind the panel last year.<br /><br />As for the ether, I have had the boat for 2 years and never needed it before, but it was cold and humid today, batt's were low, and it has sat for 3 months... hope it doens't need mechanical work.

 

[Bob_VT]

Re: RPM gauge reading double RPM???

Hmmm sat for 3 months in cold humid weather? Had it for 2 years? I would say it is time to check all your electrical connections...clean them and retighten all of them. They may be starting to corrode.<br /><br />Bob

 

[Don S]

Re: RPM gauge reading double RPM???

And like any other marine engine that has to sit for months, it probably needs a tuneup too. Should be done every spring before you head to the water first time.

 

[Bondo]

Re: RPM gauge reading double RPM???

hope it doens't need mechanical work.<br />

If it Idles at 1300/1500rpms................<br /><br />It Needs Work.............. No Doubt About It............

 

[newport dave]

Re: RPM gauge reading double RPM???

Your shifting that alpha at a "normal" idle of 1,300 to 1,500 RPM? Or do you mean that it just idles that high when cold? If your shifting it at 1,500 your tach will soon be the least of your worrys.<br /><br />Dave

 

[Don S]

Re: RPM gauge reading double RPM???

Hmmmmmmmm, missed that, thought he meant it idled nomal and the tach read 13 to 1500. <br />Between the either and the high rpm shifting he's not going to have an engine or a drive.

 

[KRS]

Re: RPM gauge reading double RPM???

It does idle high, I referred to idle gremlins on my website, I do have them. It will idle (high) for 2 minutes, then chug and drop rpms, then pick back up. If I'm idling underway and it chugs, it just dies.<br /><br />I know it needs some adjustments, I was hoping to get back to the lake, tie up at the dock (not during a busy weekend), and work in the idle, shift position, etc. Anyone a boat mechanic in Arizona?

 

[jimmythekid]

Re: RPM gauge reading double RPM???

I don't know about the tach problem, but sounds like a vacuum leak to me for the chugging and high idle. I wouldn't be shifting that thing until the idle was fixed, and the engine ran near perfect if I were you. Bad things happen when shifting @ higher RPMS. You can find a vacuum leak pretty easily, if it has one, best way is to take it to a mechanic shop that has a smoke machine, they should be able to tell you in about an hour if it has a vacuum leak,and yes (gasp) most quality auto shops have one, i am not sure about marine mechanic shops or if you like to live on the edge, AFTER THE TUNE UP WITH NEW PLUG WIRES and DIST CAP, you can use carb spray or propane. Just do it sparingly. Only very short shots, and let it evaporate before giving it the next sparingly short shot The engine will run differently when the fuel enrichment source gets close the vacuum leak. Just dont get the fuel enrichment source ANYWHERE NEAR the distributor. And make sure you have a fire extingisher handy just in case,

 

[jimmythekid]

Re: RPM gauge reading double RPM???

I just reread my last post and had this thought:<br /><br />a sparingly short shot saved serious sams sideburns, while sister sold sea shells by the seashore

 

[KRS]

Re: RPM gauge reading double RPM???

so Jimmy, do you think I should get new plug wires and dist cap?

 

[Don S]

Re: RPM gauge reading double RPM???

If the engine is running as bad as you discribe, it needs some TLC Now. A full tuneup as I said before, this includes cap, rotor, plugs, points, condensor. Plus all the tests that go into a complete tuneup, such as compression test, vacuum test, timing, dwell, etc. The plug wires if they look like original or cracked, oil soaked etc, buy all means replace them.<br />All the tests will tell you if there are any major problems with the engine. You may also need the carb rebuilt, and a filter change. Does it have a water seperating fuel filter?<br />With the thing trying to die everytime you slow down or try to shift that alone should tell you something.

 

[KRS]

Re: RPM gauge reading double RPM???

It does have a separator, I just replaced that in September.<br /><br />This forum is helpful and I appreciate everyone's help and I do read HuNdReDs of other posts.<br /><br />I am 31 yrs old, and have wanted a boat since birth. I traded my beloved '77 Toyota FJ40 Landcruiser on this boat.. the guy ripped me off. I wasn't educated well enough to check the boat when I traded.<br /><br />I have put $3,800 into the boat (motor mount replacement, new coupler, realignment, new upper drive rebuild, etc.). It appears the boat struck an object and was then left partially submerged for some time. The motor mount bolts were in mush... etc.<br /><br />This has been an exercise in utter frustration. I have a boat that cost me a vehicle plus $3,800... and it still needs work. I have not found a mechanic that I believe in and I don't know if I have the skill to do these things myself. I don't have specialized tools (dwell meter, timing light, compression check, etc).<br /><br />I will work on the idle before I put it in gear.<br /><br />Where do you buy your tune up parts from?<br /><br />Was having a hard time getting it out of gear last time out... and found where the cable posts were gouging the engine cover, probably making it difficult to move them.<br /><br />I need some help...

 

[Don S]

Re: RPM gauge reading double RPM???

You don't need real fancy tools, you can get timing lights, compression testers, dwell meters on ebay for next to nothing. Most auto parts stores carry very inexpensive dwell, vacuume and compression testers. Even pawn shops have what your looking for. <br />Here is one place for parts, but stick with Marine ignition parts, not automotive.<br />PS: you have a Delco distributor, not Prestolite if anyone asks.<br /><br /> dougrussell.com

 

[KRS]

Re: RPM gauge reading double RPM???

Maybe it's time for a new post... maybe not?<br /><br />I have been working on my idle (since being flogged repeatedly by those up ^), and have a few more questions.<br /><br />My tach (OEM) is still not correct, didn't feel a switch on the back, don't have another one to check it with... any thoughts?<br /><br />My idle is lower now, but it will idle okay for 20-30 seconds and then chug and almost die for 4 seconds, then come back up? Any thoughts?<br /><br />I read in another post that I should NOT have fuel running in that clear (well, it used to be clear, now it's hard and amber colored) hose going from fuel pump to carb. I do, and it appears to have bubbles in it.<br /><br />I manually actuate the switch at the top of the engine for disengaging the drive, and it doesn't stutter the motor. I use a screwdriver and press the plunger on the switch and bingo... stutters. It appears that the metal "arm" of the switch is bending too much when the large pivoting thing rotates against it. Any thoughts.<br /><br />As for the previous advice, I will be ordering a new set of plugs (not Champion... that's for you Don), wires and cap... and I need a coil, mine looks terrible. I have not found these on the web yet... still searching.<br /><br />Pics of my boat and engine can he had on my website below, they are high def pics and can be significantly enlarged to see detail... every rusty dirty filthy detail.<br /><br />Thank you all for your help!

 

[KRS]

Re: RPM gauge reading double RPM???

I was searching dougrussel.com for parts, then clicked the link you made for me Don.... found the parts.

 

[KRS]

Re: RPM gauge reading double RPM???

Another question <br />is my carb a rochester or mercarb, I will price a rebuild kit and gasket set.

 

[Don S]

Re: RPM gauge reading double RPM???

It has a Mercarb, identifiable by the single idle mixture screw. Rochester had 2.<br /><br />If you have bubbles in the tube from the fuel pump to the carb, then the fuel pump is leaking and fuel is pushing up to the carb. That alone will flood out the carb and is a good indication there is a problem. replace the fuel pump and your idle will probably straighten out.....Oh and clean that flame aresstor, and you might get air to the carb also.<br /><br />

enlarged to see detail... every rusty dirty filthy detail.<br />

Your engine ain't that rusty, look at this pictue from another post and compare.<br /><br />