1976 888 Fuel Questions

[ratdude747]

I have a few questions about fuel selection/practice on my 1976 Mercruiser 888

1. The engine was designed for leaded fuel (per the tags) but also on one of the warning tags (either on the engine or taped the catalog, I can't remember which), they mentioned some exception or procedure for being able to run unleaded. It has the stock heads which still have the stock valve seats. I'm reading mixed answers (here and elsewhere) on whether or not I need to source lead additive. The PO ran such in it, but 10 years ago (when he ran it last) it was a lot easier to source... seems to be a mostly online-only item. Snake oil?
   
2. The only ethanol-free fuel I can get is 30 mins away (90 octane IIRC). Due to the original tank-to-filter hose and fuel pump, I don't dare run E10 in it, even if I plan to use it up by the end of the year?
   
   
3. The boat sat for 10 years and the fuel has gone bad (despite initial signs it was passable). According the fuel gauge, there's 1/2 of the 25 gallon tank in there still. What's the best way to empty it? I bought a 3/4" jiggler pump, but the hose is (obviously) way too short to fit down the filler neck to the tank. The tank is under the rear seat... short of tearing out said seat (and the seat uphostery), pulling the tank isn't viable at the moment.
   
   FWIW, I did replace the water separating filter (old was extremely rusted internally and required a vice and a pipe wrench to remove from the housing!).
   
   
4. I assume trying to mix fresh fuel and old fuel is a great way to make a full tank of iffy garbage fuel and that I really do need to drain it.

 

[alldodge]

Your asking for an opinion so I will offer mine
Years ago octane rating was measured a bit different then now. This was also before Ethanol. Ethanol also raises octane.

In short, if it was my boat I would run regular 87 and go boating

 

[dubs283]

No need to worry about lead additives, you can use one if you want but there's not much/any need for it. 91 (supreme) E10 will be fine, not a terrible idea to toss some fuel stabilizer in it with each fill up if it's a while between uses

Probably a good idea for a full fuel system inspection along with replacing all the lines/hoses with new. A carburetor rebuild is in order as well, guessing a 2bbl Holley?

Yes, get as much of the old fuel out of the tank as possible. Might need a cleaning, removing the fuel sender will give you an opening for inspection inside the tank

 

[cyclops222]

DO NOT put any amount of E 10 into a old gas tank !!!!!!!!!!!!!!!!!!!!
It WILL DISOLVE all the different VARNISH deposits in the tank & fuel lines !!!!!!!!!!! You can then replace all engine fuel system parts as the become PLUGGED UP with the sludge.
Pump out the gas with a simple suction pump with the boat parked on anon burnable lot.

 

[ratdude747]

Your asking for an opinion so I will offer mine
Years ago octane rating was measured a bit different then now. This was also before Ethanol. Ethanol also raises octane.

In short, if it was my boat I would run regular 87 and go boating

I'm pretty sure it calls for 88 minimum. I think it's the modern "american" AKI octane rating, not the old/non-american RON.

No need to worry about lead additives, you can use one if you want but there's not much/any need for it. 91 (supreme) E10 will be fine, not a terrible idea to toss some fuel stabilizer in it with each fill up if it's a while between uses

Probably a good idea for a full fuel system inspection along with replacing all the lines/hoses with new. A carburetor rebuild is in order as well, guessing a 2bbl Holley?

Yes, get as much of the old fuel out of the tank as possible. Might need a cleaning, removing the fuel sender will give you an opening for inspection inside the tank

Fuel system is a mix:

• Tank and tank hose are original, but seem to be in good shape.
• Filter housing removed for cleaning (and removal of bad filter). Rust seemed to be the filter itself rotting, not the product of what came from the tank
• Filter to pump is the stock flared steel line
• Pump is stock
• Pump to carb is brand new A1-15 fuel hose. Old was a hack combo of flared steel and automotive fuel hose.
• Carb is a lightly used marine holley (4 barrel 450CFM) that I got a deal on (eBay, came from a motor that spun bearings twice). Before, it had a similar 4 barrel holley off a 1970's trash truck (Not marine rated!). The original 2 barrel Rochester intake and carb were long gone by the time I was gifted the boat.

I will note that I did get it to kinda run last fall on the old fuel. But not well!

Sending unit lip is stuck under the seat... If it was easily removed I'd have already pulled it.

 

[ratdude747]

Meant to post last night:

Just got done pumping it out. Filled two 5 gallon cans to the brim, no more, no less.

Wasn't able to get filler or vent hoses off. But there was a plug for a starboard-side dip tube that I was able to pull and use with a transfer pump. Not the most labor efficient way, but it worked. As does the gas gauge which I periodically checked.

Fuel didn't look bad... Smell was a bit off, but not like varnish. No rust. 1st can was black but that's because the pump was last used for changing the oil.

Once I get the old fuel disposed of, I'll get some fresh fuel and see what happens.

Edit- My front yard is non burnable enough that I once set grass on fire while welding my mailbox and it didn't spread very far.

 

[cyclops222]

Luck beats skill EVERY TIME !!

 

[ROY WILLIAMS]

Meant to post last night:

Just got done pumping it out. Filled two 5 gallon cans to the brim, no more, no less.

Wasn't able to get filler or vent hoses off. But there was a plug for a starboard-side dip tube that I was able to pull and use with a transfer pump. Not the most labor efficient way, but it worked. As does the gas gauge which I periodically checked.

Fuel didn't look bad... Smell was a bit off, but not like varnish. No rust. 1st can was black but that's because the pump was last used for changing the oil.

Once I get the old fuel disposed of, I'll get some fresh fuel and see what happens.

Edit- My front yard is non burnable enough that I once set grass on FALL while welding my mailbox and it didn't spread very far.

THE BOAT GAS TANK FLUSHING IT OUT ...THEN THE NEW 93 OCTANE GASOLINE ....gas tank MMO 2oz. 10 gallons
around 2000 year alcohol 3-6 months tank .... the gasoline is a mess MUCKY... also the carb in the take it off clean it MMO oil ......

 

[ratdude747]

Some updates from this week:

• Got another gas can and drove the 30 mins to pick up the ethanol-free 90 octane. On the way there, found a place by the lake (Hardy Lake, IN) that also sells ethanol-free gas but thinking that it would more expensive continued the extra 7 minutes to the intended place... nope, ended up spending $0.20 per gallon more. Good to know the place exists and has respectable prices since most of my coworkers (well, mostly ex-coworkers at the point) suggested going there and not the Ohio river for initial testing.
• Tried to run the boat off that to no avail... only to realize that moron forgot to drain the filter/carb of old fuel. Took the carb off and dumped it out... very yellow . After reassembly, still no luck, although after rechecking the fuel in the carb inlet it was clean fresh fuel. May still have some old fuel in the carb still... or perhaps the carb, despite being pulled in supposedly working order, has an issue.
• Did find I somehow didn't get the choke reassembled correctly (I had it apart awhile back)... and fixing that didn't help either.
• I have a carb kit on order. But the eBay seller is being relatively slow, so I likely won't have it until Tuesday or Wednesday.
  
  
• Due to not being able to get it (and the consensus in this thread being that it doesn't matter), I didn't put any lead substitute in. Hope I don't burn exhaust valves... do I need to plan on doing exhaust valve seats next winter?

 

[alldodge]

Lead can help in the long run (lots of hours) but no issue for short term

 

[ratdude747]

Lead can help in the long run (lots of hours) but no issue for short term

Which is the other thing I'm figuring.

 

[Bondo]

Which is the other thing I'm figuring.

Ayuh,.... It's a boat,..... You'll never run it long enough to matter,.....

 

[dingbat]

• Tank and tank hose are original, but seem to be in good shape.

You need to get your eye glass prescription looked at….

No way that a fuel line with a design life of 10 years looks “good” 48 years later….lol

 

[airshot]

After being stored with old fuel, all gas lines should be upgraded !! And fuel filters added, can't have to many.....

 

[ratdude747]

You need to get your eye glass prescription looked at….

No way that a fuel line with a design life of 10 years looks “good” 48 years later….lol

No cracks or leaks, but isn't hard as a rock either. If the fuel coming out was black (which the stuff that came out of the filter wasn't), I'd be worried about the hose coming apart internally. N

That said, I since have found somebody who sells 3/8 A1-15 hose by the foot and will ship it (last time, I picked up hose from West Marine in Indy)... so I will order some fresh and will swap it out as a long-term precaution.

After being stored with old fuel, all gas lines should be upgraded !! And fuel filters added, can't have to many.....

I did replace the water separator/filter... it was nasty due to the filter itself degrading. The last time it had been changed was 14 or so years ago by a boat repair shop who had left the boat uncovered for 3 weeks and flooded the bilge as a result. Among other repairs to "fix" the issue (which is another story on another thread), they replaced the filter. In the time since then, the filter's internal paint failed (went soft and peeled) and collected moisture rotted the metal to the point of the outside paint starting to bubble It was stuck so bad that I had to pull the entire housing from the manifold and separate the filter from the housing with a vice and pipe wrench. The housing itself was fine... thankfully, the damage and corrosion was limited to the filter itself. After rinsing everything off, I was able to re-install with a new filter.

The line from the filter to the pump is the factory steel line, still in visibly great shape. Ain't broke, so not fixing it.

As mentioned before, I've already replaced the fuel hose from the pump to the carb as the "original" was a badly hacked mess of stock steel line (being used as a throttle spring anchor ) and automotive-grade fuel hose. Now, it's A1-15 the entire length.

 

[ratdude747]

Pulled the carb apart after finding that clean fuel going in was becoming yellow fuel dumping out... and that accelerator valve and primary jets are not flowing. I'll add pics later, but lots of dry deposits inside with a bit of rust on internal springs. Venturries are black as coal... yeah, needs cleaned and rebuilt.

Wasn't planning on replacing floats but those are starting to crack...

 

[ratdude747]

Got everything tore down and cleaned.

Seems that idle mix screws were both bottomed out... weird. I'll have to see if there is a stock setting to try intially (for now, I have them set to 1 turn out). Also, the inlet screen was partially varnished over... and the choke heater air breather was also plugged with dirt. The accelerator pump check valve weight was seized with varnish/junk, which is likely why the accelerator pump wasn't working.

I should get the kit (and two new floats) in this week... fingers crossed, but it seems I'm finding answers to questions.

Added pics, including the old fuel line.

 

[Scott06]

Got everything tore down and cleaned.

Seems that idle mix screws were both bottomed out... weird. I'll have to see if there is a stock setting to try intially (for now, I have them set to 1 turn out). Also, the inlet screen was partially varnished over... and the choke heater air breather was also plugged with dirt. The accelerator pump check valve weight was seized with varnish/junk, which is likely why the accelerator pump wasn't working.

I should get the kit (and two new floats) in this week... fingers crossed, but it seems I'm finding answers to questions.

Added pics, including the old fuel line.

1 to 1.5 turns out is pretty standard starting point.

 

[ratdude747]

1 to 1.5 turns out is pretty standard starting point.

My thoughts exactly. May start at 1.5 because I'm told it likes fuel.

 

[ratdude747]

Floats are being slow to ship. The old ones aren't really that bad (crack is actually a surface flaw) so after a trip to the LAPS for a gasket missing from the kit, I was able to rebuild the carb.

Good news is the accelerator pump is working great and I can start. The bad news is I have a massive vacuum leak. Likely the really hillbilly PCV system and a very sketchy looking PCV valve. Right now I have two hoses shoved together with an air chuck nipple for a carb spacer barb... And a very old looking PCV valve that looks like it came from a mustang!

Are marine PCV valves any different from automotive ones? And can I use automotive vacuum hose or do I need marine fuel hose for PCV?