89 100HP Mercury fuel/starting issues

[skytracker]

I have a new to me Merc 100HP 4 cyl serial number
0C191842. Was stored and fogged last year. Good compression within 1 lb of each other. Had intermittent loss of spark to all four but fired up and ran but not smooth. Found switch box bad and replaced. Now have reliable spark. Now fuel,issues. Does not want,to keep fuel flowing. Cranks pretty good has a fully charged battery. May start but only runs for,a,few,seconds to minute. Have a clear filter between fuel pump and carb 1. I can see the fuel get to the top when primer is pumped but it starts dropping. Fuel pump was rebuilt by dealer last season. Going to replace primer bulb and then check pump. Any good thoughts?

 

[SuperEnzo]

When was the last time the carbs were cleaned? Do you have an inline spark tester to verify that you indeed have spark when it runs for that minute or so? Start simple is my motto

 

[skytracker]

Thank you for the response. Any assistance is appreciated. I am not positive on the carbs. The Orig owner said the dealer did it beginning of last season with the fuel pump rebuild. I have an ultrasonic cleaner at work. Yes, I have a spark tester and it,appears to have good spark. This is a replacement for my 95 115 with powerhead issues. Originally I had the system check beep on with the key then,off after a few seconds. Friend was helping troubleshoot and appears to have changed the warning wires around where it is on continuous when the key is on. Have to figure out,the way that is supposed to be too.Has two single wire temp BLK and TAN, BRN and BRN/WHT, that were plugged in together on the other motor at main connector to engine, and the two blue oil sensor wires. Hmm.. Don't see the TAN/BLU??

 

[skytracker]

Ok looks like several problems with fuel and carbs. I can tell #2 carb is sucking air at fittings, tightened and put new straps on. Lines look new from last year. Bottom carb not in sync with the others, shutter sticking open, will sync them later. Inlets to,all four appear clogged. Someone who knows please tell me if I can use the four carbs from my 95 115 on this??They were cleaned and rebuilt last year functional this year until powerhead locked up. Exact same head but other changes likely have to be made. Fuel pump pulse hole appeared junked up.

 

[skytracker]

Spark appears solid at this time. Blowing out fuel line and vents from the tank. I want to take these carbs off and put the ones from my 115 on. Then clean and rebuild the originals.

 

[skytracker]

Which carb rebuild and fuel pump kits do the experts recommend? I want to order some tonight. Flushed out the carb inlets and the lower carb poppets. Flushed out needle seats. Adj idle mixture setting to initial, #2 was about closed. Flushing out the existing fuel pump tonight and see what I get now.

 

[skytracker]

Back at this. Tied up with work. My anti siphon valve at the tank was full of crud, pulled and and cleaned. Seems good now, ordered a new one for insurance. Replaced the fuel lines, primer bulb, and fittings all the way to the motor. Rebuilt and cleaned fuel pump. Found the line to #1 carb deteriorating on the inside. Tomorrow I will replace them all with new.

 

[flyingscott]

You are going to have to look up both serial #s for your motors to find the difference in parts between the 100 and 115 hp motors. I am pretty sure those blocks are different as there was a design change in the early 90s and the displacement was increased.

 

[skytracker]

Yea there are some differences. The manual on the 95 says same block for the 115,125,135. The 100 says 100 and 115. All the electronics match up so far.
The carbs looks like -14 on the 115, -11 for the 100HP.