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190XT Fuel Pump Leaking?

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Fantrum View Drop Down
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Joined: 02 Feb 2021
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    Posted: 18 hours 40 minutes ago at 3:58pm
Hey everyone,

I went and started up the good ol' 1968 190XT (Series 2, I think) today to get some bush hogging done. It hasn't been started since this spring for plowing. I checked oil and all that good stuff, put in a fresh 20 gallons of gasoline. It started up just fine as it normally does, no issues at all. However, I noticed a fuel leak from what appears to be the fuel pump. I found what looks incredibly similar in the service manual (Page 194, see attached), but I believe it's a little different. The manual also says the G-2800 could have a carb, but it looks nothing alike. I will attach two images as well to show the component/leak.

When I first started it, the leak seemed like a lot. The radiator fan was blowing back against it and causing the fuel to spray all over, so it was very hard to decipher where the source was. I decided to at least let the engine warm up completely at idle (2,500 RPMs) before shutting it back off. Once it had run for about 15-20 minutes, I checked again and the leak was much less severe. I could also now tell that it was coming from what looks to be a relief hole in the lower-half (see attached). If I covered the hole, the leak would stop and the engine appeared to run exactly the same. This is where bad ideas happen.

I decided to plug the hole with some putty to get me through the brush hogging, and then I would dismantle it later and repair it properly. I went out bush hogging for over an hour with zero leaks or issues. Then I had a small hiccup in RPMs. It only lasted a couple seconds and went away. A little bit later the engine did more than hiccup and stopped. I shut it all off, turned off the PTO, etc. Restarted the engine and it idled just fine. I put it in gear to drive it back to the house and it died as I let off the clutch.

I am assuming these two are related. I currently have it sitting in the field. The putty is still in place and sealing the leak effectively - which I realize may be the cause of my current issue.

When I first started the engine today, it appeared the leak was from somewhere on the upper half of the fuel pump, but later, after it died down, it was only from this relief hole. Would anyone have any insight as to what the original issue was, why it changed as it warmed up, and why it shut down after over an hour of running hard?

Thanks!

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Alberta Phil View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alberta Phil Quote  Post ReplyReply Direct Link To This Post Posted: 16 hours 21 minutes ago at 6:17pm
I would say the diaphragm is gone in the fuel pump, and with the blocked up drain holes the excess fuel has gone into the crankcase and seriously diluted the engine oil.  It may have damaged the bearings.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantrum Quote  Post ReplyReply Direct Link To This Post Posted: 15 hours 9 minutes ago at 7:29pm
Oi. I'll have to look into that then. Thanks!

I've been looking into sourcing a new fuel pump and have found several replacements online, but a rebuild kit would be much preferred. Does anyone know of a rebuild kit for these that is still available somewhere? Or perhaps a cheaper electric fuel pump option?

EDIT:
So I walked out to the field and gave the engine oil dipstick a whiff. I would say it has a fuel smell. Guess I'm gonna give it an oil change and unplug my drain hole on the fuel pump.
Side note. I'm not saying it's a bad design, as I would assume there is a purpose behind it... But why does the fuel pump have a direct connection to the crankcase? Is it lubricated with engine oil as well, being a mechanical pump? I am ignorant on this design, but I do understand it's my own ignorance that has led to a bad decision.


Edited by Fantrum - 14 hours 43 minutes ago at 7:55pm
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WF owner View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WF owner Quote  Post ReplyReply Direct Link To This Post Posted: 13 hours 49 minutes ago at 8:49pm
Many of those old mechanical fuel pumps (on cars, trucks and tractors) were removed and a flat piece of steel made to cover the hole. The fuel pump was replaced by an inexpensive electric fuel pump.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantrum Quote  Post ReplyReply Direct Link To This Post Posted: 13 hours 37 minutes ago at 9:01pm
Thanks for that! I honestly think that's the direction that I am leaning. Keeping it original will cost me somewhere close to $300 if I can't find a rebuild kit - which is proving impossible thus far. I don't see the point in doing that if there is a cost-effective easy solution that works well.

Also. I see why the fuel pump is connected to the crankcase now... I was thinking about it and it then made sense why they have that arm sticking out of them, lol. My bad.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote im4racin Quote  Post ReplyReply Direct Link To This Post Posted: 12 hours 3 minutes ago at 10:35pm
I think I have a rebuild kit for that
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lynn Marshall Quote  Post ReplyReply Direct Link To This Post Posted: 2 hours 57 minutes ago at 7:41am
I think that I would change the oil and try and get it going again with the leaky pump. It may have major engine damage and not be worth the time and cost to replace the pump. Gasoline makes for poor lubrication on crank bearings.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantrum Quote  Post ReplyReply Direct Link To This Post Posted: 2 hours 9 minutes ago at 8:29am
Thanks, im4racin. I'll send you a message.

You're absolutely right, Lynn Marshall. I'm making a trip to town today to get supplies for two oil changes. I'm researching and trying to plan ahead for the pump, but that will only happen after it's running well.

On the topic of the fuel pump. The service manual says it runs at 5.5-6psi. I can find many electric fuel pumps that give around that, but of course they all have a range. 3-8 psi, for example. But even pumps that have nearly the same range have different GPH ratings. One gives 6gal/hour and another gives 25gal/hour. So this leads me to a few questions.
1), What sort of GPH should I be looking for?
2), Does the 190XT G-2800 have a fuel pressure regulator to help with the fuel pump not being set at a precise PSI?
3), I would assume opting for a max pressure that is slightly high is better than one that has a very low minimum, if I'm even given that choice. But any pointers on this?

Thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil48ACWC Quote  Post ReplyReply Direct Link To This Post Posted: 1 hour 40 minutes ago at 8:58am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DanielW Quote  Post ReplyReply Direct Link To This Post Posted: 9 minutes ago at 10:29am
I believe the rebuild kit for that pump is CK-4220, available from 'Then and Now Automotive' in Weymouth, MA. Very nice folks to deal with. And they can confirm for sure that it's the part number for the rebuild kit for the 190XT's pump (I'm 99.9% sure it is, but I am going from memory from a few months ago, so there's a chance I'm wrong). And if that's not the part number, they can put together a kit for yours. They list a few kits online, but have way more in-stock and all the parts make rebuild kits for just about every mechanical fuel pump. I've got three rebuild kits for mechanical fuel pumps from them.

Just make sure you get the check valves around the right way when you assemble it - I've had to re-do a few pumps that folks have tried to rebuild and foolishly put both check valves around the same way.

As an alternative, you can just get a cheapo $30 electric fuel pump from Amazon. But it absolutely needs to be no more than 4 psi - preferably less. Or if you do use a higher-pressure pump, you'll need to put an external regulator on that you can use to reduce it to 2-4 psi. That's what I did for my 180 gasser with the 2800 when its fuel pump went and I needed to get it going asap.

Although the manual says 5-6 psi, you have to remember that with a mechanical pump the flow backs as the engine RPM decreases. With an electric pump, it's putting out the same flow/pressure regardless of engine RPM, and you can easily overpower your float with more than 4 psi and cause all sorts of hard-to-diagnose flooding and rich-running issues.

Whatever the case, you want to fix that diaphragm asap, as it will dump a pile of gas into your crankcase if it gets bad.


Edited by DanielW - 6 minutes ago at 10:32am
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