Old crossflow idle issue, and re-starting issue

[numlaar]

Hey all,

So i have a really old Evinrude crossflow (1983 175HP).

Its pretty much what I call a "frankenmotor". It is made up of some 79' parts, some 83' parts (majority), and some 90' parts.

Anyway, this is my question:
At idle it wants to stall at anything below 1K rpm. To keep plodding along in no wake, i have to kick it up a bit more than normal (like 1100/1200). So if i try to set it down below this 1k RPM, it just flat out dies. Secondly, after its been warmed up, its terrible to restart. I have to fire it up with the throttle arm advanced, it will fire up, rev up and then when i put it back to idle it dies again. The only way to keep it going is to re-choke it to get it to go for a sec, then its ok. Lastly, it has what I call a dead zone... once off idle, I can take off full throttle get it up on plane, then back it off... but when I back it off and it goes under 4k RPM, it just gets sluggish, and starts to go bleh..... and wont stay up on plane. Like if i try to cruise at around 3500 it just wont run and wants to die down and come off plane. After 4k RPM the thing screams, and runs all day no problem, but man that really drinks the fuel. I can run it at any RPM above 4k and its no problem at all. I've run it hours like this, and never an issue.

First thing people will probably say is "carbs" but here's whats been done:

All 3 carbs rebuilt, with factory kits, and a real carb soak, (not just sprayed out with cleaner)
Link & Sync
two new coil packs,
new plugs,
new wires,
two new fuel pumps

Also boat has a new gas tank, all new fuel lines, a new fuel/water seperator, and new under cowl filter. Fresh gas, with fresh mix using XD 50 oil.

The block is a mix of the 1983 parts and 1979 parts (4 pistons are 83', two pistons are 79'). But compression is almost a dead even 100 on all 6.

Anyone have any thoughts on what this might be? I can work around it, but its just problematic, especially when trying to come in slow to the dock, and having it stall all the time.

[Capt. Bob]

New plugs but have you pulled them since you installed? If so, what do they look like?

Checked all hose connections for air leaks?

Carb rebuild done properly (that you know of)?

[flounderpounder225]

With that age, have you done a compression test yet?  Last one I saw that had those symptoms had a dead cylinder?  Just something to check.  make sure your throttle is all the way open, all plugs removed, and as stated before see what your new plugs look like after you ran it.  good luck

[GoneFission]

Sounds like a vacuum leak or broken/stuck reed or timing problem to me.  Check all the hoses and make sure the carb nuts are tight.  Did you check the reeds when you had the carbs off?  Maybe something got sucked in there too...  Sometimes you will get a poor idle but run good at high speed if the timing is off (too far retarded), so you may want to check the timing as well.  

We have a couple Johnny Rude experts on the site here, and I am sure one of them can chime in with some good ideas as well.  Good luck!

[Rhojo]

Sounds like a vacuum leak or broken/stuck reed or timing problem to me.  Check all the hoses and make sure the carb nuts are tight.  Did you check the reeds when you had the carbs off?  Maybe something got sucked in there too...  Sometimes you will get a poor idle but run good at high speed if the timing is off (too far retarded), so you may want to check the timing as well.  

We have a couple Johnny Rude experts on the site here, and I am sure one of them can chime in with some good ideas as well.  Good luck!

+1

check the reeds.
http://www.classicaquasport.com/phpBB3/viewtopic.php?t=11414

[fitz73222]

Check the wiring coming out of the timer base and look for breaks. Try to manipulate the wiring while the engine is running using a stick or something not conductive and see if you can change the engines attitude by sweeping the wiring front to back or back to front to mimic rotation of the timer base and see if it runs differently at idle. Understanding this is a pre-mix engine does she smoke excessively at idle? Also do a spark check, all plugs out, normal idle position, look for weak or no spark and then fully advance the throttle, if you have a binnacle control box you can do this with the box pegged in neutral and check spark again, look for a difference between idle spark and pegged spark. This points towards a wire issue in the timer base harness. This makes a lot of assumptions that everything else is right in the setup. The quirk here is that you can choke it restart which points towards a fueling issue but I've seen where choking to restart can mask a base timing issue, so I would make no assumptions just yet that the engine is linked and sync'ed correctly without verifying it. Incorrect  float heights can do this also.

[numlaar]

New plugs but have you pulled them since you installed? If so, what do they look like?

Checked all hose connections for air leaks?

Carb rebuild done properly (that you know of)?

Plugs clean, have run it a few times since replaced, and they are all even, slightly oily, and no milky/water/metal
Yes carbs have been re-done twice, just to be sure.

With that age, have you done a compression test yet?  Last one I saw that had those symptoms had a dead cylinder?  Just something to check.  make sure your throttle is all the way open, all plugs removed, and as stated before see what your new plugs look like after you ran it.  good luck

Yes they were all almost a dead even 100 (basically 100 +/- 4) so like 98, 101, etc.

Sounds like a vacuum leak or broken/stuck reed or timing problem to me.  Check all the hoses and make sure the carb nuts are tight.  Did you check the reeds when you had the carbs off?  Maybe something got sucked in there too...  Sometimes you will get a poor idle but run good at high speed if the timing is off (too far retarded), so you may want to check the timing as well.  

We have a couple Johnny Rude experts on the site here, and I am sure one of them can chime in with some good ideas as well.  Good luck!

I will re-check all the hoses and connections, was new carb mount gaskets, all new re-circ hoses, all new fuel hose, actually its 100% new hoses under the cowling for everything. The reeds were all clean,, tightly closed, and flexible. I took the set out of the 79, they were the cleanest and in best shape. Timing I have not checked... that's possibly where I am lacking, I basically took the throttle arm off, did the powerhead rebuild, and stuck it back on, so I didn't really change the setting from what it was before. I do know, that before the pistons burned up, it did idle just fine.

Check the wiring coming out of the timer base and look for breaks. Try to manipulate the wiring while the engine is running using a stick or something not conductive and see if you can change the engines attitude by sweeping the wiring front to back or back to front to mimic rotation of the timer base and see if it runs differently at idle. Understanding this is a pre-mix engine does she smoke excessively at idle? Also do a spark check, all plugs out, normal idle position, look for weak or no spark and then fully advance the throttle, if you have a binnacle control box you can do this with the box pegged in neutral and check spark again, look for a difference between idle spark and pegged spark. This points towards a wire issue in the timer base harness. This makes a lot of assumptions that everything else is right in the setup. The quirk here is that you can choke it restart which points towards a fueling issue but I've seen where choking to restart can mask a base timing issue, so I would make no assumptions just yet that the engine is linked and sync'ed correctly without verifying it. Incorrect  float heights can do this also.

Thank you very much for the info. I will do my best to try all of these things and let you guys know... I have just sunk too much into this thing to trash it at this point. (even though I do want something newer). I have taken it to Evinrude twice, and they charge me 500bucks to not even fix anything... first time told me had a bad block (water in #6) (so I changed it), second time told me a I had bad fuel, so I had it all pumped out and put in all brand new gas (tank is nearly new).  (also 225 bucks), so that's 1250 not including the work I have done.

[Georgie]

Can you provide any more descriptors re: the stall?  Does it slowly wind down, wobble like she's struggling to stay alive and then die?  Does it sputter and cough or sneeze right before it cuts out?  Does it just stop dead the second you get it below 1000RPM?  She should be able to stay running at least down to about 700 RPM.  The compression numbers are good (a tiny bit low, but nice and even) so that's one potential issue you can eliminate...though a leak down test will give a more complete picture.  

Since you're convinced the fuel delivery is not the problem after multiple carb overhauls, you theoretically are left with an air leak, timing/sync, or spark as the root problem.  Can you test the strength of spark coming from each coil to see if it jumps the required gap?  Also, you can check the resistance in all of the components of  your electrical system to see if they all fall within factory specifications.  I can get you specs if you need them, but you really would need a factory manual for the exact procedures.  Running at night with the cowl off is also an easy way to see if you have a short in the ignition system b/c you'll either hear the snapping or see the blue spark jumping to the block.  Recommed you take time to verify your entire ignition system due to the age of the wires.  Could very easily have a crack in the insulation somewhere.  

I doubt it's a reed issue b/c you'd be left with one or two plugs looking markedly different from the rest.  Vacuum leak screwing up your mixture is certainly still a possibility.

You have old style butterfly choke or newer primer solenoid on your engine?  Primer solenoids can sometimes leak which would definitely screw up idle.

[futch13]

100 psi compression is getting low, do you have tstats in motor and is it running at 125-145 degrees?  Todays fuels need the heat to burn, you can't remove the tstats anymore.  If motor is running at correct temp, pull intake covers and check piston skirts.  If they are smooth and the cyl walls have lost their crosshatching then you are not building enough crankcase vacuum/pressure to run the fuel pumps and pull fuel charge from the carbs.  Compression test will not show this problem.

[fitz73222]

100 psi compression is getting low, do you have tstats in motor and is it running at 125-145 degrees?  Todays fuels need the heat to burn, you can't remove the tstats anymore.  If motor is running at correct temp, pull intake covers and check piston skirts.  If they are smooth and the cyl walls have lost their crosshatching then you are not building enough crankcase vacuum/pressure to run the fuel pumps and pull fuel charge from the carbs.  Compression test will not show this problem.

Good idea Loye, I thought compression was low for a crossflow but didn't give it much thought since it was even. i have seen worn/broken sealing rings between the crank journals cause "confusion" in the crankcase pulses from internal blow by and affect fuel pump operation. Since the engine seemed happy at high speed and appeared to make power I was looking at it from a different direction. I haven't seen many engines that were just slap wore out but this may be the case. You always stir good thinking and I appreciate it.

[futch13]

The old cross flows are notorious for this...especially the 2 and 3 cylinders.  I have seen a couple v-6s but the majority have been the smaller motors.  OP also stated he (or someone) used used pistons when rebuilding, if cyl walls were honed at the same time then piston clearance can also be a factor.

[kaptainkoz]

Two ideas come to mind before you tear the motor apart. Ive done many crossflow carbs and one sent me for a loop for a few days until I did the simple "toothpick" test. On the crossflows you have an external Idle jet located inside the carb intake throat at the "1 o clock" position on the left side opening and at the "11 o clock" position on the right side opening. They are hard to see as they are deep in the throat, almost against the butterfly, and inset a bit. If they are there (based on age, some have them some don't) they are hard to miss as they are literally screw in brass jets. Run the motor at idol (or as best you can) and use a simple toothpick to plug up a single jet hole, one at a time. What should happen is the motor should want to die within 5 seconds. Go on to the next jet, and the next and the next. Why does it want to die? The jet is allowing in a precise amount of air which is in turn pulling in a precise amount of fuel with it. When you clog it off the vacuum pulls in a disproportionately high amount of fuel and chokes the motor to a stall. If you go through all 6 and they all similarly stall then you can be certain your idle circuit is not clogged. If you have a carb or 2 that there is no change then that means that circuit (or fuel pathway or tube) is clogged, and running that cylinder super rich, thus bogging your motor to a stall.
so yes, even though Ive rebuilt carbs myself, there was some little particle of crap that broke free and clogged it up before I even got the thing in the water. It happens, but at least there is a simple test for that.

Second. I don't think this is your initial issue as it isn't critical enough to stall it, but if you figure it out then definitely do this after to bring the motor from running rough to much smoother.  I don't know why this isn't more documented but it is critical to a motor running rough perfect. On the Evinrude part site for 1983 175 on the intake manifold page is part #7, 0392988  CHECK VALVE & FILTER. These look like little brass nipples that connect the pencil-thick diameter rubber hoses from under the carbs to the side of the cylinder case. You, me and everyone else thinks they are simple nipples to connect hoses to. Not true, they are check valves for the recirculation circuit. I don't fully understand it but they help equalize the fuel within the crank case... or something like that. I don't really care what they do, all I know is after you change them it takes an idol from rough to smooth. The problem is they are up to $35 each now from the $18 each just 4 years ago. they are expensive when you have to buy 6. They will not correct for a "lean sneeze" or a stalling motor, but they will take a crappy running motor and smooth it out. I believe one telltale sign of failed check valves is noticeably darker lower 2 sparkplugs. In any event, not the first thing I would do in your case but If you do iron it out then it would be worth it to change them.

You can test them by taking them out, hooking up a hose and blowing then sucking through it. Its a check valve so you should clearly be able to pass air through it ONLY one way. Or simply stated if you don't know what they are and they were never changed then they are definitely clogged, or stuck open and SHOT. Ive pulled them out where 5 out of 6 were dysfunctional.

Lastly, there may be a plastic Tee check valve connecting a slightly larger diameter rubber hose from the top of the case near the carbs, to under the carbs, tee'ing in the one of the check valve hoses. This one is easy to spot if you have it as it is black plastic with a directional arrow on the side of it. it should be on the port side of the carbs if your motor has one. that one is about $30 as well and should be replaced.

Sure, it could be worn skirts or worn crankshaft rings but I think there are many issues that can make crossflows run like crap before you get to that point. I have soft rebuilt (all gaskets and hoses, but not cracking cases) almost a dozen crossflows and have never run into vacuum/skirt issues. Im not saying it isn't possible because it is, but ive gotten many old crossflows to run great.