115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

[syl]

Hi i just rebuilt my 115 with a 140 block the only difference is the bigger exhaust.Now when i try to start it i got to spray gas in the carb and give it full throttle and when it starts it revs at max when i bring the throttle down a bit it revs fine at half throttle but when i try to bring it to idle speed it completly stalls.what can my prob be timing not enough gas or do i need the 140 carb????????? <br />115 Jonhson 1978

 

[DHPMARINE]

Re: 115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

syl,<br /><br />"only difference being the exhaust" got my attention.So I searched a bit,and here is what I found.<br /><br />85,115,and 140 blocks are different.The heads are different,but the 115 and 140 share the same head gasket,so I suppose the bore is the same,while the 85 is probably smaller.<br /><br />exhaust cover (between the heads is the same for 85 and 115 HP,but differenr for the 140 (bubble ?)<br />is this the difference you mean?<br /><br />You can look this up yourself at johnson.com,I think it is under engine diagrams.<br /><br />I knew someone who tried to do this years ago,so I knew where to go to find this.<br /><br />DHP<br /><br />Oh yes,the carb jets are different,but so isn't the bore of the carbs.

 

[syl]

Re: 115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

dear DHP, although the info is well appreciated the info does not help unless you are suggesting that we change the jets in the carb to bring it up to 140 hp standard carb jets, we need to know if the bigger exhaust on the 140 block needs more fuel, or if the timing is wrong or if we have a low fuel problem which seems the most likely because it only starts when we spray fuel in the carb ports and use full throttle , syl

 

[djzyla1980]

Re: 115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

If you can get it to start by spraying fuel into the carbs... then look at fuel supply. I could be wrong but the jetting should only affect the high speed jet. Have you torn the carbs down and took a look??

 

[syl]

Re: 115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

no i dint but i will do that and let u know what should i lokk for ? am not to sure but i will take them down and clean them and all that good stuf so let me know if i should look for some thing ok thanks.

 

[steamboatwilly]

Re: 115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

Look extra close at low speed jets.

 

[OBJ]

Re: 115 1978 Jonhson Only starts in max throttle and spraying gas in carb.

Any rebuild should include the carbs. What was the reason for the rebuild in the first place? <br /><br />I recently had a similar engine come through my shop. Was supposed to be a 115 (77'). Pulled the hood and it was a bubble back. Checked the welsh plug on the block and it was a 140 block. It also still carried the carbs from the 115. The owner bought the engine new and it had been rebuilt with the 140 block several years ago.<br /><br />Your problem is probably fuel as posted above. Also check the choke plates are closing all the way when trying to start.<br /><br />You should dismantle the carbs, soak the out in carb cleaner and follow up with compressed air through all the passages. Install new rebuild kits. As James Williams posted, check the jets real close.