PDA

View Full Version : PCM 351 Fuel Issue


wakeslave
09-07-2013, 04:10 PM
Hey everybody, Im brand new to the board here, but not new to owning or working on inboards. I was just looking for a couple tips before I bought some new parts.

84 PCM 351, its had a bit of a rough idle and hesitates when getting on the throttle with a skier. I was planning on rebuilding the carb beginning of next season, because i don't want to rebuild then have it sit over the winter. Anyway, last week the idle got a little worse while on the water, then it died and I couldn't get it started. With a squirt of ether, or gas down the carb, it does fire, but wont stay running. Obviously not getting fuel.

I changed the filter (fram cartridge on the side of the tank, kind of a pain) and hoped it would fire up, but no luck. after cranking for a while, trying to get it to pump fuel up to the carb, i checked the drain plug in the filter cartridge and still no fuel. Is there anything else I can do/check before replacing the pump? Also, are new fuel lines a must with that?

Any tips would be great. I've used this forum as a reference for a while, its good to be a part of it now and Im looking forward to talking with you guys!

ted shred
09-08-2013, 03:36 PM
Sometimes you have to prime the filter/water seperator. Unscrew the canister and fill it with fuel and put it back on. This should help. There is a clear hose attached to the fuel pump, if the pump goes bad this hose will have fuel in it.

wakeslave
09-08-2013, 03:58 PM
okay Ill give it a shot. I was hoping that the pump would pull it through, but i guess not. In the past, fuel pumps have just died on me, and didn't cause any rough idle or hesitation when accelerating, which is why i assumed it was the filter. Is my logic correct here?

Cloaked
09-08-2013, 04:44 PM
You log-on / log-off fix-it guys kill me :D

Several things to consider...

Start at the fuel cell. The 84 has an eleven inch fuel pick-up tube with a screen at the bottom of it. I have seen that become obstructed for fuel pickup. Remove and clean or replace the fuel pick-up / sending unit. I replaced one about 3 years ago on an 85 fuel cell so I can attest it is not a hard job and you'll need one sooner than later. While you're there reroute the ground wire away from the filler neck and find a ground point upstream toward the engine somewhere.
You will have to remove the fuel cell to do this work. Order a new filler hose and cut the old one off. The old hoses are hard and attached to a barbed or ridged connection. You'll save lots of time and headache by just cutting off the old hose and put in a new one. You'll also save on scratches on the deck when you try and try to remove it from that vantage point (and it still won't come off).

Next, at the top of the fuel level sending unit can be (not on all applications) an anti-siphon valve inside of the connecting elbow where the fuel line is attached. I have seen those become an issue where they gum up and tend to stick in a semi-closed or closed position. Replace it with a standard elbow connector (no valve). I think by 1984, MC had stopped installing those but check for sure.

Next is the consideration of an old fuel line that has gummed or collapsed due to ethanol lace fuel. Replace the fuel line with new material.

Next is the fuel filter. Replace it with a new one, period. It probably needs it for the sake of knowing you have a new one. If not, replace it anyway. I am aware of a fuel filter in a canister located just under the fuel pump, mounted on the port side stringer. Make sure you have that replaced with a new one also (if in fact MC put a filter in that location). Most early boats have one there.

Next is the fuel pump. Your 84 is a PCM engine and that fuel pump diaphragm will eventually dry out, shrink, and/or deteriorate. It just stops pumping fuel. No warning (typically). Replace said fuel pump, but be cautious as to how you remove the metal fuel line between the pump and the carb. DO NOT force or wiggle the line out. Either remove the pump away from the fuel line OR lift the carb away from the fuel line. Been there more than once. Just take the extra time to lift the carb from the base (also plan on have two new base plate gaskets for resetting the carb.). Reinstall in the same manner, setting the carb down onto the fuel line. Don't be lazy and go trying to shortcut and wiggle the line out from the carb. Be sure and get a PCM designated pump, as an Indmar pump (appears to be the same pump) will not work due to the positioning of the fuel line entry points.

That's it aside from making sure you have fuel in the fuel cell before you go checking all of these checkpoints.

.

wakeslave
09-08-2013, 07:51 PM
Definitely full of fuel. Im gonna start by filling the canister and priming the lines. Like I said, I just did the filter with no success and it's mounted on the port side of the fuel cell. Totally wish it was in the bilge. If I do new fuel lines Ill def mount it to the stringer under the pump. And I do have the cell with no anti-siphon valve. I had it out a few months back to do a transom repair after the platform lags pulled through (not fun). Thanks for the tips, ill let ya know how things turn out.

Cloaked
09-08-2013, 09:09 PM
I had it out a few months back to do a transom repair after the platform lags pulled through (not fun). I did that to an 85 model not too long ago... I share your sentiments...

.

east tx skier
09-09-2013, 03:19 PM
You log-on / log-off fix-it guys kill me :D

Several things to consider...

....

Next, at the top of the fuel level sending unit can be (not on all applications) an anti-siphon valve inside of the connecting elbow where the fuel line is attached. I have seen those become an issue where they gum up and tend to stick in a semi-closed or closed position. Replace it with a standard elbow connector (no valve). I think by 1984, MC had stopped installing those but check for sure.

....


At the risk of being called a log-on/log-off fix it guy, I'll chime in on the ASV. ;)

It is my understanding that this is a coast guard requirement if the fuel line runs beneath the tank. I don't think MC stopped using them. My late 90s CC has one. If your fuel line develops a leak, the ASV ensures that you don't fill the bilge with fuel. I have replaced two ASVs in four years. And removing the fuel hose from the barb in that tight space is not something I have been too successful at short of cutting the fuel hose.

If you have faith in your fuel line not to develop leaks, a straight pass through barbed fitting might be the answer. If not, buy an extra ASV and, when you replace the fuel line, buy a little extra length so you can cut it to replace a few ASVs in the years to come without worrying about running out of slack.

WA Nautique
09-09-2013, 03:50 PM
ETS - I pulled the fuel line this weekend on mine, ASV was plugged full of dried fuel. I like to use a 90 pick to shove between the fuel line and the barb. use some WD-40 or equivalent and spray it into the gap created by the pick (between the barb and the hose) push the pick around the fitting and the WD will significantly loosen the hose and you can pull it off without cutting or destroying it.

wakeslave
09-09-2013, 11:28 PM
I was hoping to get to working on it by now, but my car is in the shop and I was supposed to have it back by now. I got rear ended and now have nothing to tow my craft from storage to my house to work on it.

I actually ordered a new pump, found 1 in stock on amazon for 50 bones, so I figured id give it a shot. As much as I love DIM, amazon for half price is worth the try. It is the airtex pump, not the carter, but I have heard good things about them so its worth a try. What are you guys' opinions? I'm only gonna put it on if i conclude that the fuel lines are not blocked.

If the lines are good and the pump is good, the pump should have no problem pulling fuel from the tank, even if the filter canister is empty, right? I'm trying to troubleshoot this in my head (due to my boat being stuck in the storage yard).

WA Nautique
09-10-2013, 02:31 PM
the fuel filter not being full will cause problems. the high volume pump on my engine (carter) is a vane type pump. it will pump liquids, but uses the liquid as part of the seal . Air will compress too much and not pump well. IF the pump looses its prime, it is difficult to get it back with such a long fuel line run, especially since there will not be the inherent siphon as you would have if the line was full of fuel. I would second the post above about putting some fuel into your filter canister before trying to run the pump.

east tx skier
09-12-2013, 05:25 PM
ETS - I pulled the fuel line this weekend on mine, ASV was plugged full of dried fuel. I like to use a 90 pick to shove between the fuel line and the barb. use some WD-40 or equivalent and spray it into the gap created by the pick (between the barb and the hose) push the pick around the fitting and the WD will significantly loosen the hose and you can pull it off without cutting or destroying it.

I have an assortment of picks bought specifically for this task and, sadly, I have never had any luck with them in getting that barb to let go of the fuel line. I tend to try to give it a good work out before I eventually give up and cut the hose. :o

wakeslave
09-15-2013, 03:57 PM
Update:
Alright. Filled the filter canister with fuel, sucked the air out of the line to the pump, so I knew I had fuel to there and... nothing. I didn't have fuel showing in the overflow line, but I replaced the pump anyway. Works excellent, fired up and I'm loving it... except for the fact that my alternator died 5 mins after I got it going. Prob gonna take it to get rebuilt, cause new ignition protected ones from DIM are pricy buggers. Unless anyone knows of a cheaper/better option.

Cloaked
09-15-2013, 05:35 PM
....Next is the fuel pump. Your 84 is a PCM engine and that fuel pump diaphragm will eventually dry out, shrink, and/or deteriorate. It just stops pumping fuel. No warning (typically). Replace said fuel pump,
.

Update:
Alright. Filled the filter canister with fuel, sucked the air out of the line to the pump, so I knew I had fuel to there and... nothing. I didn't have fuel showing in the overflow line, but I replaced the pump anyway. Works excellent, fired up and I'm loving it... except for the fact that my alternator died 5 mins after I got it going. Prob gonna take it to get rebuilt, cause new ignition protected ones from DIM are pricy buggers.........
......... Unless anyone knows of a cheaper/better option.

===> http://www.dbelectrical.com/c-7765-pleasurecraft.aspx

.

east tx skier
09-16-2013, 10:25 AM
My fuel pump just gave out this weekend after 15 years of service. At least it did it at the ramp.