454 cough, sputter, hiss

[salty87]

1987 pcm 454 inboard, newer edelbrock carb, new distributor/wires/coil. used to run like a top but sat for a few months.

....running like junk, stalls after 10 seconds on the hose. will re-start but stall quickly again. often see smoke coming out of flame arrestor on stall, hiss sound too. almost seems to reverse rotation when it dies.

water separator is new this season. i got the gas at the same station i always get gas for my cars. it's not more than 4 months old, sta-bil'd recently. i haven't hooked up external tank but i don't think it's the gas. water separator is still good, no water.

i replaced the distributor/coil/wires this summer and plugs are new this season. my old distributor was all rusted up. boat ran great once or twice with new distributor but stalled on my last outing. there was a very noticeable hesitation while running (at 2600 rpms). i tried to get home at idle speed but it stalled and sucked up some water. i blew the water out and got her re-started but something is wrong.

timing seems wrong, has me wondering if i messed up the timing chain when i had some plug wires crossed. the timing chain is not OEM though, i replaced it a few hundred hours ago when i had a front seal leak.

could it be fuel pump? could timing chain get messed up from crossing plug wires?

i can't even check timing now because it won't stay running long enough. when i give it some throttle it bogs down, coughs, stumbles and either recovers to bog again or stalls. ugly

i've been messing with this too long and am stumped. would appreciate some help getting a handle on this.

thanks

 

[DHPMARINE]

Re: 454 cough, sputter, hiss

Check for water in the cylinders again,even if the water seperator filter is ok.It does sound like a water problem.

We chased a similar problem earlier this year,and found the exhaust manifold was leaking water into a couple of cylinders.

DHP

 

[Don S]

Re: 454 cough, sputter, hiss

Does the choke work?
Was the carb mixture adjusted after you installed it?
Have you replaced the plugs?
What distributor do you have?
Have you looked at the old plugs for water after you run it?
Have you done a compression test or a vacuum test on the engine?
You say you wasn't sure the timing was adjust right, WHY aren't you sure, did you use a timing light?

 

[salty87]

Re: 454 cough, sputter, hiss

dhp...that sounds very close to home. i've pulled the plugs a few times now (they're new this season) and they've been pretty wet. more than just gas. this past sunday when i started it up, there seemed to be more smoke (grey/white) than before but it runs so bad and stalls so quick that i wasn't sure. there's no water in the oil. manifolds are original but i inspected them about 200 hours ago and they looked pretty good. fresh water boat exclusively.

don...the choke does work. i adjusted it a few weeks ago just to be sure it was set right. plugs are new this season, mallory marine distributor. i haven't done a vacuum or compression test lately. my comment about the timing was mostly an observation. i do have a timing light and did time it back when it ran good a couple of times. my observations are the slight reversing when it stalls and spits gas up the arrestor (hisses and smokes), even when i did time it there was a barely noticeable stumble with the timing light that later became very noticeable on the water (i'm assuming they're related), and after it stalls on the hose i can hear water coming out of the exhaust when normally that flow would stop.

sorry for the length, i appreciate you guys' time

 

[Don S]

Re: 454 cough, sputter, hiss

my observations are the slight reversing when it stalls and spits gas up the arrestor (hisses and smokes),

That sounds like it's dieseling, what is the idle rpm set at? Should be 700 rpm or less. Make sure the static timing is where it should be and the mechanical advance is working properly and recheck the idle mixture adjustment.
Also, make sure the static timing and the idle mixture are all adjusted while it's running at 700 rpm

 

[salty87]

Re: 454 cough, sputter, hiss

the idle is (was) set right around 650. there's no real idle now, it's either try to give it gas and bog it down and stall or no gas and it stumbles and maybe stalls. it doesn't run good and then just shut down sloppy.

i'm not sure how to check timing with it running like it is. i might be able to get someone to jack with the throttle while i work the light but it doesn't run long.

the mechanical advance worked like a champ the few times it ran good, last time would have been in sept. even that last time out when it stalled and sucked up water, it seemed like it was trying to run smooth but kept hesitating like the tank vent was clogging or something. i opened the filler cover to be sure and it made no difference.

i'll try the idle mixture to see if it stabilizes it at all so i can check timing. i'm also going to pull the plugs again to see what they're looking like.

thanks

 

[Reel Poor]

Re: 454 cough, sputter, hiss

It really sounds like an ignition problem to me. Check the cap and rotor for cracks and/or moisture. Be sure the coil wire is not arching to one of the primary post (possible cracked coil tower).

Could be water in the fuel also. Take a sample into a pan or jar and see what the fuel looks like. If there is water in it, it will seperate.

 

[Bondo]

Re: 454 cough, sputter, hiss

timing seems wrong, has me wondering if i messed up the timing chain when i had some plug wires crossed.

Are you Sure that the Plug Wires are on Right now,..??..??.......

Why wouldn't you check the Static Timing,+ Look to see if all the Valves are moving, as well as In Time...??........

 

[salty87]

Re: 454 cough, sputter, hiss

Are you Sure that the Plug Wires are on Right now,..??..??.......

Why wouldn't you check the Static Timing,+ Look to see if all the Valves are moving, as well as In Time...??........

it ran really good for a trip or two...new distributor seemed to make a big difference. i don't think i would have gotten all of that with crossed wires and i've checked them and re-checked, etc. it timed pretty good with timing light but still had a hesitation that you could see with the light. water running out the exhaust when on the hose and the engine not running really has me puzzled, that doesn't usually happen. and now, with gas smoking out the carb when it stalls, seems timing related but i'm no pro.

i'd check static timing (if you're referring to at idle) but it won't run for more than 10-20 seconds without stalling. i'm going to give it a try.

looking at the valves...now we've reached the end of my experience. do you mean to pull the valve covers? (pls don't cringe at that question, i've never worked on valves)

i'm headed out of town tomorrow afternoon. going to hopefully have time to pull the plugs and slap the timing light on her before i go.

reel- water seperator has checked out good but i am going to pull the plugs again to see what they look like. cap, coil, wires, most of ignition is new when i did the distributor.

if i can steal a few minutes to check those tomorrow i'll post back; otherwise, you guys have a happy thanksgiving and i'll pick up here next week.

 

[salty87]

Re: 454 cough, sputter, hiss

another thought...this was the first time i replaced a distributor. i didn't get the oil pump right the first time although i barely got off the trailer before alarm went off. i think i'm good based on how it ran after i fixed that but i'm doubting myself all over the place now.

 

[Reel Poor]

Re: 454 cough, sputter, hiss

cap, coil, wires, most of ignition is new when i did the distributor.

It's still worth a look. You stated in one of your other post that your old distributor was all rusted up. There may be a problem with the boat design letting water get on the distributor and ignition system causing a problem.