78 85 hp johnson javelin

[Mike sm]

Engine cranks right up seems to run right for about 15 or 20 seconds then starts missing and will not idle and I have unspent fuel coming out the prop. Here’s what I have done so far. Checked compression and I have 120,115,120,115 .Checked continuity of spark plug wires, all good here, replaced spark plugs with proper champion plugs, checked to see if all plugs were firing, good here. Checked air gap at 7/16 all jumped the gap. Also checked plug gap. Replaced all the coils with new ones. Replaced the stator and rectifier. Did not see anything wrong on visible check of old stator. Got a new power pack and tried it on each bank. Disconnected the big red plug and cranked it with a remote starter switch. Got the oem carb kits and went through them and set the floats to the proper drop. checked every connection every where and all looks good or was cleaned to look good. With everything I have done so far, it runs exactly the same, bad ! Any thoughts ?

 

[tphoyt]

Have you checked your fuel for contamination as in water? Tanks vents working properly? Unspent fuel could be a running rich problem or a cyclinder or two not firing properly.
just trying to get the ball rolling for you here as no one else is chiming in.

 

[duffg130]

Engine cranks right up seems to run right for about 15 or 20 seconds then starts missing and will not idle and I have unspent fuel coming out the prop. Here’s what I have done so far. Checked compression and I have 120,115,120,115 .Checked continuity of spark plug wires, all good here, replaced spark plugs with proper champion plugs, checked to see if all plugs were firing, good here. Checked air gap at 7/16 all jumped the gap. Also checked plug gap. Replaced all the coils with new ones. Replaced the stator and rectifier. Did not see anything wrong on visible check of old stator. Got a new power pack and tried it on each bank. Disconnected the big red plug and cranked it with a remote starter switch. Got the oem carb kits and went through them and set the floats to the proper drop. checked every connection every where and all looks good or was cleaned to look good. With everything I have done so far, it runs exactly the same, bad ! Any thoughts ?

I'm having a similar issue on a 1989 100hp johnson. I have excess oil running down the skeg, a lot of oil. I think its was from me constantly pushing the key in and trying to start it. I disconnected the VRO system and I'm going to try it on a small tank with 50:1. My spark plugs are fouled out. I ordered new ones so once they get here I'll give it a try. Not sure if you have a VRO but if so, maybe try disconnecting. Keep us posted on your progress. Hoping it helps me as well.

 

[CaptnKingfisher]

Engine cranks right up seems to run right for about 15 or 20 seconds then starts missing and will not idle and I have unspent fuel coming out the prop. Here’s what I have done so far. Checked compression and I have 120,115,120,115 .Checked continuity of spark plug wires, all good here, replaced spark plugs with proper champion plugs, checked to see if all plugs were firing, good here. Checked air gap at 7/16 all jumped the gap. Also checked plug gap. Replaced all the coils with new ones. Replaced the stator and rectifier. Did not see anything wrong on visible check of old stator. Got a new power pack and tried it on each bank. Disconnected the big red plug and cranked it with a remote starter switch. Got the oem carb kits and went through them and set the floats to the proper drop. checked every connection every where and all looks good or was cleaned to look good. With everything I have done so far, it runs exactly the same, bad ! Any thoughts ?

Struggling with this ..you're identifying a miss, which would be ignition circuit and you've replaced the entire ignition system with no change. Id go through the wiring and grounds and clean the connections. Try starting it at night when it's dark out with your remote starter and look around the coils to check for arcing. How do the plugs look? Maybe you can identify which cylinder(s) missing if you've have a plug or two that are especially oil fouled

 

[oldboat1]

In a fuel sample, water would appear at the bottom (using a glass jar).

Operating temp should be around 140F. 160F ia overheating, measured at top of heads. Too hot to touch is too hot to run. Impeller change is first priority if the motor is new to you.

 

[Mike sm]

Have you checked your fuel for contamination as in water? Tanks vents working properly? Unspent fuel could be a running rich problem or a cyclinder or two not firing properly.
just trying to get the ball rolling for you here as no one else is chiming in.

Thank you for your reply, I believe it’s certainly running rich. I’m using a brand new plastic omc tank and fuel line, fresh marine fuel and evinrude oil. I bought 4 of those in-line spark testers and it appears their all hitting the same without any missing at all. I have had a few of these v4’s in the past and just never had this problem. With the amount of fuel mud coming out the prop I would think it’s more than one cylinder. I do believe that it is ignition related. Once again, Thank you for your insight !

 

[racerone]

There is no VRO on 1978 models !--------Check fuel pump diaphragm.-----And how did this motor run for you last season ?----Water pump impellers need to be changed every 5 years or so.----Perhaps remove bypass covers ( 4 of them with 6 screws each ) to inspect pistons / rings.

 

[Mike sm]

I'm having a similar issue on a 1989 100hp johnson. I have excess oil running down the skeg, a lot of oil. I think its was from me constantly pushing the key in and trying to start it. I disconnected the VRO system and I'm going to try it on a small tank with 50:1. My spark plugs are fouled out. I ordered new ones so once they get here I'll give it a try. Not sure if you have a VRO but if so, maybe try disconnecting. Keep us posted on your progress. Hoping it helps me as well.

Thank you for your reply, this motor is a 1978 and that was before the vro’s . I’ll certainly keep you posted as this has become a “quest”.

 

[racerone]

VRO was introduced in 1984 model year.

 

[Mike sm]

Struggling with this ..you're identifying a miss, which would be ignition circuit and you've replaced the entire ignition system with no change. Id go through the wiring and grounds and clean the connections. Try starting it at night when it's dark out with your remote starter and look around the coils to check for arcing. How do the plugs look? Maybe you can identify which cylinder(s) missing if you've have a plug or two that are especially oil fouled

Thank you for your reply, let me add that I just bought this motor and it had NGK spark plugs in it when I got it. Looked to me that the last time it was running it was running perfect, all the ceramics in the plugs were that perfect Hershey bar color that you want to see. With the new champions I put in it, I really can’t tell anything from the plugs at this point, they all look the same. I did do the night test and man, was I hoping I would find it arcing somewhere. Like I said originally, it cranks right up, and seems to be fine for about 15 or 20 seconds, then without moving the cold start lever the rpms drop and it starts slobbering until it dies. At this point I have unplugged every connection and cleaned every terminal on the entire motor. It’s like after 15 or 20 seconds something is breaking down. Thanks for your input ! I’ll keep hacking at it..

 

[Mike sm]

Struggling with this ..you're identifying a miss, which would be ignition circuit and you've replaced the entire ignition system with no change. Id go through the wiring and grounds and clean the connections. Try starting it at night when it's dark out with your remote starter and look around the coils to check for arcing. How do the plugs look? Maybe you can identify which cylinder(s) missing if you've have a plug or two that are especially oil fouled

Thank you for your reply, let me add that I just bought this motor and it had NGK spark plugs in it when I got it. Looked to me that the last time it was running it was running perfect, all the ceramics in the plugs were that perfect Hershey bar color that you want to see. With the new champions I put in it, I really can’t tell anything from the plugs at this point, they all look the same. I did do the night test and man, was I hoping I would find it arcing somewhere. Like I said originally, it cranks right up, and seems to be fine for about 15 or 20 seconds, then without moving the cold start lever the rpms drop and it starts slobbering until it dies. At this point I have unplugged every connection and cleaned every terminal on the entire motor. It’s like after 15 or 20 seconds something is breaking down. Thanks for your input ! I’ll keep hacking at it

 

[racerone]

Not uncommon to buy an " issue motor " these days.----Put away your axe.-----Stop replacing parts.---Start some orderly trouble shooting.-----These motors in good condition run very well indeed.

 

[Mike sm]

There is no VRO on 1978 models !--------Check fuel pump diaphragm.-----And how did this motor run for you last season ?----Water pump impellers need to be changed every 5 years or so.----Perhaps remove bypass covers ( 4 of them with 6 screws each ) to inspect pistons / rings.

Thank you for your reply , the compression test would indicate that I don’t have anything going on here I would think..really didn’t think it was fuel pump related as it seems that getting fuel is not and issue. If the floats are working properly I shouldn’t have any excess fuel. Do you think I missing something here ? Thanks for your input..

 

[racerone]

Well------I could rebuild your motor powerhead and lower unit without glancing at a manual.-----So do not make any assumptions.---Check the fuel pump diaphragm !!!

 

[Mike sm]

Well------I could rebuild your motor powerhead and lower unit without glancing at a manual.-----So do not make any assumptions.---Check the fuel pump diaphragm !!!

Okay, you sound confident, I’m just an amateur at this so, I’ll certainly take your advice and check it out and let you know what I find. Thanks for your help !