Guzzling gas then sipping it

8ender

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Nov 1, 2018
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1974 Chrysler 45hp. Motor seems to be in tip top shape. New plugs, new fuel lines, fuel pump diaphragm in good shape, did the timing, points, water pump, and thermostat. It starts and runs great.

It's attached at a 1969 Chrysler Cadet which is about 14" and weighs 300-400lbs. I have maybe another 100lbs of gear in there.

I had it out on the lake over the course of a few days and it was absolutely destroying fuel. I'd burn about 3 gallons in 20 minutes. WOT or cruising range didn't seem to matter. It's doing about 4950 rpm at WOT with a 12 1/2 pitch prop.

Here's the weird part. On the last day on the water it lost it's appetite for dinosaur goo and burned only 1/8th of a tank on the same 20 minute run to town. I hadn't changed anything. Weather was about the same as it was the other days.

My thoughts are that the needle valve is letting gas through but could that explain such a massive fuel consumption? I skipped replacing the needle when I overhauled the carbs because it looked like it was in good shape.
 

jerryjerry05

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That sounds more like the fuel pumps bad??
The diaphragm streched or a hole?
The recirc system might be clogged.

If the needle was sticking it would more than likely flood.
 

8ender

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Diaphragm is in good shape. The recirc system on mine doesn't match the 1974 diagrams I'm seeing. I have a line running from the bottom of the reed casing and looping back to a port near the top of the reed casing on the other side. Nothing I can see coming from the crankcase. Looks like my motor is 1972-73 I think.

Looking at my parts motor from 1969 it has the same two ports but they tee together and drain into the leg. No drain on my leg.
 

jerryjerry05

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The older models just dumped the excess right into the water.
Then I guess the EPA or someone got involved.

Post a pic of the hose.
 

8ender

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I hope these photos are clear. The hose appears to plug in to the bottom of the reed casing on one side and then loops around and is plugged into the casing on the other side.

On the 1969 engine I see these two same ports but they tee off and drain into the leg. No drain on mine.

On the 1974+ engines it looks like there's a puddle drain system on the starboard engine block behind the throttle linkage. Nothing like that on mine.
 

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The Force power

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I found this on #axrules, is this what your looking for? check their site
 

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Nordin

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Jerryjerry you want a partslist or service manual?
I have factory partslist for 1972 35Hp and 45Hp and the service manual for the 35, 45 and 55Hp.
Partslist 1972 or 1973 will be almost the same.
 

8ender

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I'd love the partslist if you'll share it Nordin. I can't find anything online prior to 1974.
 

Nordin

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8ender give me your private email adress in the PM and I will send you the partslist in pdf.
Jerryjerry I have your private adress, will send the service manual tomorrow.
 

8ender

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I had it out on the lake this weekend and wasn't really able to gauge fuel mileage well because I had four on the boat and the engine was noticeably lugging to get on plane. Did a decent 28mph once there.

At the end of the day though I could feel the RPMs fluttering up and down at cruise almost like a cylinder was cutting in and out. Still idled well otherwise. Between that and the cable coming off the pulley steering wheel I decided it was time to head to the docks. Haven't done any troubleshooting on the new issue yet. Could be related, could be something new.
 

8ender

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Looked at the 1972 parts list Nordin sent out and I'm confused. It shows a puddle drain cover with a hose barb behind the throttle as well as a few other things my powerhead doesn't have. Starting to wonder if my powerhead is lying about her age.

Is there any identification on the block I can match against the tag inside the cowl?
 

Nordin

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8ender they changed the drain at the intake manifold about 1971-72 I think.
The early design was two hoses from each cylinder where the reed valve assembly is mounted and these hoses connect to a Y block which is called a Y connector with check valve and then one hose from the Y right down to the midleg.
I do not think there is a check valve in that Y block.

Later they changed it to one hose from top cylinder in the lower part of the cylinder just under the flywheel to the lower part of number two cylinder crank case.
Then one hose from the top cylinder port intake cover to the "dogbone" cover.
 

8ender

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Interesting. So I have the older design with the two ports on the reed valve assembly but no port to drain to the leg even though the tag says it’s a 73’. Hose just goes from one side of the reed assembly to the other. I’m starting to think someone put an older power head on here.

Any ideas on fixing this and identifying the power head?
 

Nordin

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If the two ports from each cylinder in the intake manifold are connected with a hose then someone has done something with it.
The engine will not run properly after a while due to "floding" the intrake/crank case with unburned fuel/oil mix.
You can fix it by connect the hoses and connect to the midleg by bore a hole and fit a fitting htere.
There are a flat spote in the casting where it used to be earlier.

This not so good for the enviorment but to modify to the later design is really difficult.

BTW there should be a mark in the block casting, a circle with the year in the middle.
Located at the side of the block, do not remember exact position of it..
 

8ender

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I can see the flat spot where the barb would have been. The swapped powerhead doesn't surprise me. There's been some weird stuff on this engine including the throttle cam being ground down by the previous owner for reasons unknown. I bought it for $100 and the owner told me he was fed up with it. Seems he tried everything but actually learning how the motor works.

If I'm going to pollute the lakes I may as well compression test the 55hp 1971 parts motor I have here. The wiring is messed up but the motor makes the right shoosh shoosh noises turning the flywheel. Anything I should know about swapping a 71' powerhead onto a 73' cowl and leg other than the mess that's already there?
 

8ender

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Nov 1, 2018
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I have a Force 50 parts motor as well that has all the gear for the recirc system but I'm going to assume I can't swap that because the drains I need won't be there.
 

jerryjerry05

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The hose from one to the other, just put in a T and drain the excess overboard??

They didn't make many changes in the mounting hardware, so the blocks just might swap??
 
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