Gas in Oil - Fuel Pump Failure? (1 Viewer)

S4Cruiser

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I'm still learning my new to me 40 and am in the process of baselining the fluids. While changing the engine oil, I noticed the oil seemed 'thin', drained rather quickly and had a gas smell (PO used 15w40). I sent a sample to Blackstone but don't want to wait a month to start troubleshooting.

I also have noticed a strong gas smell from the truck. I have it parked in the garage and it's so strong that you can't spend much time in the garage with the doors closed without catching a buzz (not good).

A little background on the truck - Runs great and feels really strong, has a rebuilt 76 2F with 39k miles, new OEM carb, 60 series distributor, and new starter. The fuel pump is mechanical and was replaced via OEM 10 years ago. Gas tank was replaced with OEM steel 5 years ago but the truck has probably only seen 5k miles in this time.

No noticable gas leaks around the tank, lines, carb, etc. I'm leaning towards the fuel pump or gasket failing and pumping the crank full of fuel. I haven't pulled the plugs yet to see if they are wet, but I'm thinking that they are fine since the truck runs so well.

I want to replace the pump it to rule it out. I'm under the impression that OEM is not available from Toyota anymore but some have used the Kyosan fuel pumps from Napa.

Thoughts? Anyone have any other ideas/troubleshooting recommendations before I start throwing money at the problem?

:beer: - Jon
 

76FJ40

Old Fart
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Sounds like a fuel pump diaphram to me. Does it leak gas from the fuel pump weep hole while it's running?
 

S4Cruiser

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So would wet plugs point towards the carb and if the plugs are fine then the pump would be the culprit.

I'll check the weep oil in the pump during lunch.

Thanks for the help so far!!
 

3_puppies

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check your oil level if overfull probably the pump. if that is the case do not run the rig. Your oil is diluted thus not giving good protection to vital internal components.
Fix it and change the oil and filter.
 
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My friend had this problem with his 2F, refilled it with some used oil and ran it without the fuel pump, by feeding gas through the carb, turned out gas going through one of his piston. Other words hole in the piston. I hope you have a bad fuel pump unlike my friend. This was his very rusty plow truck.
I also have a spare 2F that is doing exactly the same thing.
I have no time to play with it r now, but I am going to run it again with electric pump and hopefully that will fix the problem.
I already have the e pump and the engine is already on the frame, but it is at my friend's place and I have no place for it. Too much snow in my yard.
 

1911

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I want to replace the pump it to rule it out. I'm under the impression that OEM is not available from Toyota anymore
I bought an OEM fuel pump from a dealer a couple of months ago for my 1980. They didn't have it in stock but got it from the regional distributor in a day or two.
 
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A non-firing piston can cause this. A piston can be non-firing for a number of reasons from huge vacuum leak to broken plug wire. Also a leaky float bowl in your carb can drain into the crankcase. After letting the truck sit overnight, where is the fuel level in the carb window?
 

S4Cruiser

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A non-firing piston can cause this. A piston can be non-firing for a number of reasons from huge vacuum leak to broken plug wire. Also a leaky float bowl in your carb can drain into the crankcase. After letting the truck sit overnight, where is the fuel level in the carb window?
The truck has set since early afternoon yesterday and you can barely see any fuel in the carb window. During idle yesterday it was in the middle of the window.

The truck runs really smooth so I don't think that one piston is not firing unless it is super subtle...

Thanks again for the help. I've got an FSM on order that would come in real handy right about now :doh:.
 
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Your strong odor of gasoline in the truck/garage could be a cracked and/or dry rotted gas tank filler hose or vent hose or loose clamps, or a defective gas tank cap. Wet gas won't be evident so maybe inspect more closely. Just a suggestion, good luck and please advise. :)
 
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I had the exact same issue, the smell in the garage would get pretty strong. I finally did discover the fuel pump was leaking through the weep hole. It was not enough to be easily noticed but it was enough to stink up the garage.
 

S4Cruiser

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My plan for the weekend is...

-check each and every fuel line and clamp to rule them out.
-check the fuel filter and clamps
-check the gas cap to make sure the gasket material isn't done

I checked the weep hole last night and couldn't see signs of leaking but ordered a fuel pump and gasket from SOR yesterday and will replace my current one when it arrives (probably Tuesday) to rule it out.

I still need to figure out why gas is draining from the carb while the truck sits in the garage. I got a falshlight out and took a good close look at the carb and it might be leaking. I noticed that the EGR tube coming off of the carb was not capped off so I'll get that fixed this weeked too. I also noticed the gas smell seemed the strongest near the carb. Thoughts?

I hope it doesn't need a rebuild as it's a near brand new OEM carb...

BTW the truck is desmogged with aftermarket headers (forgot to mention that in the first post)

Half the fun of owning a 40 is fixing it yourself right ;)?
 
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Check the carb; make sure all the bolts are tight. My 74 carb will drain as well, not sue why but it does not seem to affect anything. If your fuel pump is bad it could leak fuel into the crank case. What do your spark plugs look like? Good money it's the Fuel Pump.

Good Luck!

Corey
 

S4Cruiser

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Update

Quick update and more questions.

I replaced the gas cap, tightened all fuel line clamps. Also replaced the fuel pump, oil and oil filter. The oil I drained had <30 miles on it and wasn't near as thin or smelled of gas as the previous oil change (the one that raised my initial concern).

I took the truck on a quick drive (was 25 degrees and no top) and it seems to run great other than a very minor miss at idle...I'll be replacing the current plugs (Bosch) with ND's this weekend. The 40 probable idles as good as my 80 :D.

Question - I seem to be getting horrible gas mileage. I know it's no hybrid but damn I can almost see the needle move during hard acceleration from a stop and through the gears. What type of mileage is typical out of a tank (stock size for a '74, 2F, 4 speed, 33s, headers and 60 series dizzy/ignitor)?

Could my carb be running extremely rich? I don't get a stuble during accel and it idles fine. How would I check/know if I'm running too rich?

I'm new to the 40...maybe I'm just paraniod, but want it to be right :meh:

-Jon
 
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S4, I think if you were running that rich, the plugs would turn black very quickly. How do they look after a run?
 

S4Cruiser

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S4, I think if you were running that rich, the plugs would turn black very quickly. How do they look after a run?
Here's two pics of plug #1. They all pretty much look the same. Sooty but not wet. Thoughts?
Plugs 001.jpg
Plugs 002.jpg
 
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It looks like you are running a bit rich, you need to turn in your mixture adjustment screw a bit. Clean/replace your plugs and turn your mixture screw in a bit… about a 1/4 of a turn, be careful you don't want to run to lean, try a setting and drive it then recheck your plugs. The FSM should give you a base line of were to set the mixture screw. You need to understand that the 40 will at best get about 14-17mpg, and this will depend on gearing, tire size, carb settings, and the overall condition of the engine, don’t forget you are driving a big cinder block. Currently mine will get about 15 MPG, the engine is strong and I am running 31" tires with the stock gearing. Oh and the gas tanks are some what small so the gas quantity will appear to go down very fast.

Good Luck!
Corey
 
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S4, those are dark but they dont look like the coal black that I was getting when I was running too rich. And that would happen very quickly to new plugs, not sure if you said yours were new or not. If not, throw some new ones in and then go for a drive, it shouldnt take too long to turn them jet black (if it is running too rich). IMO those plugs dont look like it is running so rich as to be your strong gas smell problem but they do need to replaced.
 
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