1989 Mercury 70hp 3 cylinder won't start issue

Smurph

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Jun 12, 2012
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20
Sold my 1989 Party Barge w / 1989 70hp Mercury 3 cylinder to a neighbor. Nice guy and family, so was totally up front about everything, and wouldn't you know it, they've encountered a no start issue. If I had sold it to someone out of state, it would've never gave a problem probably. My luck . . So they called me and weren't mad, just wanted to know if I could come take a look. I did, and found that you can crank and crank, and the engine won't fire up. Squeeze bulb is tight, fuel in tanks.
The boat ran and done everything right for them, until they replaced one of the 2 fuel tanks, with a new 9 gallon tank. They stated at first everything was good, but later noticed while out on the lake riding, that the new tank had collapsed inward, as if the vent on the cap was closed. They fiddled around, then abandoned the effort and just emptied that fuel into the other tank and went on about a fun day, and its ran fine for several days, until yesterday when it quit while under slow speed pulling up to pier and backing down off throttle.
After checking it out the best I could while boat still in the water, I noticed that the main fuel hose from the front of the engine where your auxiliary fuel tank hose connects to the motor, from there the hose that connects to the fuel pump would spray fuel once you pump on the bulb. Bulb gets tight, but never the less hose leaks. So I pull that hose loose from pump, snip the end of hose where split was, reinstalled, pumped it up and the engine still will not start. After cranking and cranking noticed the bulb again needs to be pumped till tight. Found that odd, why . .
My question is, could the fuel pump be damaged from trying to suck the fuel from that tank, that either had the air vent closed off, or a defective cap. I replaced the gaskets and diaphragm last year with a kit, so I know its not a dry rot issue.
Any advice would be much appreciated. I plan on going back over this morning and just check some more.
 

huggyb1972

Petty Officer 1st Class
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Apr 1, 2013
Messages
249
Could've collapsed the fuel hose. You could open the drain on the carbs and see if there is any fuel getting to them.
 

racerone

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Dec 28, 2013
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38,579
Kill switch checked ?---Are they lifting the fast idle lever ?-----Are they pushing the key in while cranking it over ?
 

Smurph

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Jun 12, 2012
Messages
20
Could've collapsed the fuel hose. You could open the drain on the carbs and see if there is any fuel getting to them.

Found out this morning that they have been running on the other tank for several days, after, that tank collapsing issue. So after that it done alright, until just Sunday, eased up to pier to fuel up, and died, and hasn't hit a lick since. Checking today for fire at plugs, they are not wanting to pull it out yet till all the simple stuff has been done. Makes sense. Thanks huggyb.:)
 

huggyb1972

Petty Officer 1st Class
Joined
Apr 1, 2013
Messages
249
A quick shot of starting fluid is a fast way to see if it's fuel or ignition related. Open the throttle give a 1/2 second shot of starting fluid close throttle and try to start. If it starts go to fuel system if not look at the ignition module. CDI electronics has a very good resource for ignition system testing.
 

Silvertip

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Sep 22, 2003
Messages
28,771
Pull the plugs and see if they are wet. Yes - No! Yes = no spark. No = no fuel.
 
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