Hard start

[DTM]

I have an 86 alpha one 5.7l mercruiser. I am having trouble getting it to start the first time after it has sat for more than 10mins or longer. It will start first pop if I turn it on and off straight away. After it sits for a while it smells very fuely. I don't pump the throttel before I start it so that is not the problem.

I have just replaced the ignition sensor and done the timing to 8btdc. It runs beautiful but it's just hard to start after sitting. Because I did the timing and replaced the sensor, do I have to adjust the air fuel mixture?

 

[cr2k]

Re: Hard start

Check the carb bore after you have run it for awhile. If it has fuel or fuel mist in it either your float level is too high or the anti siphon holes on your main jets are plugged.
Does it start if you pump it?

 

[DTM]

Re: Hard start

I've just had it running I noticed the choke has been diconnected - it's probably half my problem and yes i did have to pump it but it has been sitting for 24h.

 

[Lowlysubaruguy]

Re: Hard start

I dont know if the 86 alpha has an electric fuel pump but my later model Alpha seems to eat fuel pumps its it most common issue. They seem to be slow priming themselves or just waking up. I never put a fuel gauge on mine to know . First see if its got spark to at least one spark plug first this helps rule out distributor cap it should jump at least half an inch then id crack the line at the carb and be sure to dissable the ignition not pull the coil wire make it so there no spark ( burning boat down while checking for fuel pressure not good idea) let it sit overnight and see if its moving fuel well enough to fill the carb quickly. If not you know its a fuel delivery issue then you need to check for power and restrictions in the line or tank pick up.

One other thing mine has an oil pressure switch that cuts the fuel pump and the oil pressures slow to build after sitting make sure your running premium oil filters. Mine had a fairly new fuel pump that just couldnt pick up prime for 10 to 20 seconds so i hot wired a horn switch to pre prime it as I put the boat in the water made the starts quick enough to deal with it for a couple of seasons then I put another new pump in it.

Now the other issue that has now become part of this type of problem is the accelorator pump in the carb mines dead combine that with a slow to build fuel pump and youve got a 25 second crank seems like a week of sundays if the boat launch is plugged up I like to dump and go. Carbs being overhauled before it goes back in this spring. not to mention this is hard on starters and drains a battery.

 

[DTM]

Re: Hard start

sorry no electric fuel pump

 

[Bondo]

Re: Hard start

sorry no electric fuel pump

Ayuh,... Which Carb,..??

 

[ktbarrentine]

Re: Hard start

sorry no electric fuel pump

My '90 5.0L exhibited similar probs and I tracked it down to cracked fuel pump diaphragm. Would run ok when started, but would put excess fuel into carb air horn (via the fuel pump sight-tube) and essentially cause a flooded condition prior to restart. I've been told that the ethanol in fuel these days is not so good for the diaphragm...

 

[grewvin1]

Re: Hard start

86 could have rochester 4bbl, float needle seat could be dirty causing carb to flood after shut down.

 

[DTM]

Re: Hard start

The carby is a rochester quadrajet 17080561 1607

 

[skydiveD30571]

Re: Hard start

Are you cracking the throttle open when you start it? Not pumping, just cracking it open a little. Mercruiser recommends it.

 

[DTM]

Re: Hard start

No I'm not, I'll try that and if it doesn't make any difference I will check the fuel pump and put a kit through the carby. Thanks for your help everybody.

 

[Don S]

Re: Hard start

Try the starting methods before you start trying to fix things that aren't broken.

Carbs do not start like the fuel injected engine you have in your car or truck. Carbs take some getting used to, and every carb is just a little different in what it takes to start them.

 

[DTM]

Re: Hard start

Thanks Don.

 

[skydiveD30571]

Re: Hard start

That's good advice I didn't listen to. I had the exact same circumstances last year (being 24 I've never operated a carbed vehicle before) and after a summer of diagnosing, buying tools, replacing parts, taking apart carbs, and utter annoyance, it turns out it was user error the whole time.

 

[DTM]

Re: Hard start

I took the boat out today and tried the starting method that skydive sent me and it started a lot better. Also I've been trying to start it with no throttle at all after its warm, in fear that I'd flood it. I tried the quarter throttle and good job. Thanks again. Love this forum