PDA

View Full Version : 8.1L enigne surging when first cranked


Ole Miss Rebels
07-26-2012, 04:17 PM
i have an '08 xstar with 8.1L. have never had any issues with it. five weeks ago i put it in the water and cranked it up. when the engine got up to 160 degrees i took off and it topped out at 22 mph. i turned everything off, rebooted everything i could and it did it again but got up to 30 mph. withing 30 minutes it was running perfectly. no issues since UNTIL last saturday when it did it again only this time it surged and missed and just didn't run smoothly although it got up to speed faster. within thirty minutes of running it was running good. i took it out the next day and it ran perfectly from crank up to shut off including taking the rpm's up to 5000 and a top speed of 42 (with the 1475 X 15.5 oj prop. so, what do you guys think is going on? bad fuel, water in fuel, fuel pump, fuel filter, ecm, spark plugs, clogged injectors? thanks, trying to trouble-shoot/narrow it down since the nearest dealership is 250 miles away.

scott023
07-26-2012, 04:20 PM
Mine acted similarly when I got a bad batch of fuel on a trip out west...

willyt
07-26-2012, 04:39 PM
something definitely doesnt sound right with your top speed... my MCX star hits 39. I gotta think with an extra 100 horsepower you'd hit something over 42.

if it ran rough it might be an injector... pull your fuel pump out and check your fuel filter (really easy to take out the fuel pump assembly. if it missed might be your spark plugs too (how long has it been since you've changed them?). the first thing i would do is try and pull codes from the boat, should give you a lead on whats going on.

I also believe that indmar came out with an ECM flash in 09 that helps the big block run better.

Ole Miss Rebels
07-26-2012, 05:16 PM
Mine acted similarly when I got a bad batch of fuel on a trip out west...

thanks, scott. i am hoping it is only a bad batch of fuel. but i have put several in several tanks in-between the two episodes. a friend suggested i try SeaFoam fuel additive in the event it is water in the fuel.

Ole Miss Rebels
07-26-2012, 05:20 PM
something definitely doesnt sound right with your top speed... my MCX star hits 39. I gotta think with an extra 100 horsepower you'd hit something over 42.

if it ran rough it might be an injector... pull your fuel pump out and check your fuel filter (really easy to take out the fuel pump assembly. if it missed might be your spark plugs too (how long has it been since you've changed them?). the first thing i would do is try and pull codes from the boat, should give you a lead on whats going on.

I also believe that indmar came out with an ECM flash in 09 that helps the big block run better.

thanks willyt, i assume the top speed is close to correct considering how low i have it propped down. i didn't hit the rev-limiter or i could have gotten another two mph out of it. how often should i change spark plugs? do they run better after they warm up? something makes me think it is a fuel quality or fuel pressure issue.

willyt
07-26-2012, 05:33 PM
fuel pressure is really easy to check - you can go to a napa and buy a gauge that connects to your schrader valve. should be north of 58 PSI.

ok, get it on the top speed, i hit 5k rpms with my 14.25x14 (now thats propped down..). Sure you put the right octane fuel in?

indmar manual says every 300 hours/every 2 seasons i think. i'm on place for that to be every season for me though...

scott023
07-26-2012, 05:52 PM
thanks, scott. i am hoping it is only a bad batch of fuel. but i have put several in several tanks in-between the two episodes. a friend suggested i try SeaFoam fuel additive in the event it is water in the fuel.

Fueling up at the same station?

Ole Miss Rebels
07-26-2012, 06:23 PM
yes, scott. same station for the entire life of the boat.