6.2 hard start when cold and sputter at low rpm

brandonmayberry

my fv342 has twin 6.2’s. My port started becoming very difficult to start after it’s sat for a week. I would crank the key and it would never start. Once I let off the key it would sputter and sometimes try to start. I’d work the throttle and it didn’t seem to really help but eventually I could get it to start. Once it ran for a bit it’s easy to start again. Now I’ve noticed it’s still doing that and also when going to give some gas it will start sputtering at about 1100rpm until about 2000rpm. Over 2000 it seems to run ok and act fine. I’ve replaced IAC and distributor cap. Both engines draw from both tanks. Fuel water superstore have not been changed but I would think that would affect it through your all rpm range. Also it doesn’t appear to be getting to Normal operating temperature. It gets to about 130 degrees while the other runs warmer by about 15 degrees or so. It also seems to want to idle high after coming off the throttle then levels itself out to normal idle rpm . Any thoughts? 

212rowboat

sounds like either a weak fuel pump, a failing fuel pressure regulator, or a stuck (open) injector on the offending engine... have someone turn the key on but not start it while you have your head above and between both engines... you should hear the fuel pump pressurize the system to the proper rating before stopping... does one (port) take longer or sound different? 

brandonmayberry

It does sound different, but it has always sounded different than the other. My fuel pressure tester stopped working awhile back so i cant check manually with the gauge, but i hook my RINDA DIACOM to it and when running an cranking it shows proper fuel pressure (same as the other engine).

davidbrooks

How old are your spark plugs and wires?  I was having the same thing happen to me and ended up doing a full tune up. Cap, rotor, wires, plugs and filter and it had a huge difference.

brandonmayberry

Plugs and wires are original. I am changing them this weekend as i figured it was an easy place to start and it needs them anyways. Im hoping that will fix it but we will see. It was weird how it just started out of the blue when its not been having any issues.

Dream_Inn

Well, if they are original then you are way overdue.  it would surprise me if it was the cap/rotor.  I know someone that had the older 342 and always had problems with water getting in the cap.

brandonmayberry

I replaced the cap already

brandonmayberry

Well changed plugs and wires. Engine starts right up now but still not running right. Plugs must have fouled out from the computer over fueling due to it running too cold. Engine temp is only getting to about 130. I replaced the thermostat and it’s still the same issue. Fires up and idles great but when I go to give it throttle it sputters and seems to misfire. Only thing I have left is either the ecm or coil but don’t know how either the coil or ecm would keep the engine from getting to operating temp. Any thoughts? 

brandonmayberry

Also haven’t swapped the map sensor, but again not sure how any of this would cause and engine to run 15-20 degrees cooler than normal. 

brandonmayberry

Ended up doing compression check on this engine. was low on like 3 cylinders. couldnt figure out why as the headgaskets looked good. Mechanic said by the time he pulled the block for a compression check etc. etc. we might as well replace it. Put a new shortblock in it and fixed the problem.

Sorry to revive old threads but wanted to inform of the outcome so maybe someone else doesnt chase problems as much.

Handymans342

Now you have a new boat