Mobile mechanic in coastal Virginia?

[bigred]

Sean:: It look's like your baby just wants to stay with you!!!!lol

[Sean]

Success.... sort of :-(

I got the new fuel pump in place with a minimum of fuss. It did require another 3-hour round trip, this time to the nearest Ace Hardware open on Sunday (the much closer one is not) for a 3/16 key.... the pump has three weep holes spaced around the shaft housing and there are plugs in two of the three, and they needed a 3/16 square drive. No such thing, near as I can tell, at least out in these parts, so I bought the key stock and used a Crescent wrench to turn it. So far no leaks and my Tru-Blu dope worked fine.

Now she starts up and runs on whatever I put in the Davco bowl. Sometimes she'll run well beyond that; we managed maybe five minutes at high idle. Then she runs out of fuel.

Watching after shutdown, the Davco gradually fills back up, telling me that the new pump is drawing a good vacuum and the Davco bowl is holding vacuum. I thought maybe the main supply line was obstructed; took it off and blew compressed air through it all the way back to the tank.

After horsing around with the supply for way too long I decided to just stick a hose from the Davco inlet to a 2-gallon can, and, lo and behold, it has the same problem. Eventually quits due to fuel delivery, but then the Davco fills back up.

I am now suspecting a problem inside the part of the Davco I can't see. Or maybe it's the check valve, which I think is right at the inlet. Anyone taken one of these apart? I'm hunting for an exploded diagram right now.

-Sean

[DoubleEagle]

Maybe water accumulated in the bottom of the Davco before you stored the bus, and now there is internal corrosion in it or any check valves. Open the drain valve and collect what you get and see if water separates out. Check the body of the Davco for any sign of cracks.

[Sean]

Ta Da. And now, I've seen everything. Including a two-way check valve (or maybe that's a zero-way check valve, depending on how you look at things).

I took the check housing off the Davco, and was surprised to find a cage and a spring but no ball on what was obviously a ball-check arrangement. Peering down inside, past the ball seat, I could see what looked like a ball.... After taking the inlet fitting off the other side (a street ell mated to an angled flare fitting), I found the check ball more or less wedged on the end of the street ell:



Stuck to the end of the ell like this, it was very effective in preventing backflow to the tank, but it was nearly equally effective in preventing forward flow as well.  This is the actual ball seat, where the ball *should* have been resting (the cage and spring that would go over it have been removed):



I was able to get the ball off its perch, clean it up, and put it back on it's seat with the spring and cage over it. The spring is a bit sloppy and I stretched it a bit to fit; Davco makes a "check valve service kit" that includes a new ball, spring, and cage, and the buyer should probably service this soon, but for now it is working mostly as intended. I suspect the damage to the ball means it will leak down over time.

I'm scratching my head as to how this could happen. I'm thinking that perhaps a day with a large temperature swing caused the fuel pressure in the bowl to rise just as the orifice expanded, thus pushing the somewhat malleable ball back past its seat and out the housing orifice. I'm sure I'll never know, but it's one of the weirder failure modes I've seen over the years.

Once I had the ball/spring check valve back to mostly normal, the engine fired right up and ran normally. It's quite possible that, had I discovered this obstruction earlier, I might have gotten the beast primed and running without replacing the fuel pump. Then again, I could not get it running even with the Davco bowl full and the top cap open, so clearly the lift pump was tired if not finished.

I am very relieved to be past this particular hiccup, and I am grateful to the folks here who helped steer me in the right direction. It's been a long three days.

-Sean

[DoubleEagle]

This the kind of thing that happens when things sit for a long time, but it is always satisfying to solve a problem like this. I hope the new owner appreciates what you have gone through.

[Oonrahnjay]

...   it's one of the weirder failure modes I've seen over the years.  ....

-Sean 

     Yeah, definitely ... but a good illustration of my fave motto "never assume that you only have one problem ..."

[eagle19952]

my guess, the check valve diminished the pumps useful life.

who knew

ps clifford did say "unless the check valve is leaking by" ... which i guess it would if the spring did not hold it on the seat...

tho i am unsure of the Davco flow ...

[Scott & Heather]

Simply amazing. Wow. So glad you solved this and so glad you can wish the buyer farewell and Bon voyage! Now go relax on your boat somewhere


Sent from my iPhone using Tapatalk

[oldmansax]

     Yeah, definitely ... but a good illustration of my fave motto "never assume that you only have one problem ..."

X2

Glad you got it going, Sean.

TOM

[Mike in GA]

Sean, I knew that you would eventually get to the bottom of this challenge. Well done!

[luvrbus]

Glad you got it going the Davco can be a real PITA,I had my doubts about the fuel pump being bad but I was to far away to help you 

[Seangie]

Ta Da. And now, I've seen everything. Including a two-way check valve (or maybe that's a zero-way check valve, depending on how you look at things).

I took the check housing off the Davco, and was surprised to find a cage and a spring but no ball on what was obviously a ball-check arrangement. Peering down inside, past the ball seat, I could see what looked like a ball.... After taking the inlet fitting off the other side (a street ell mated to an angled flare fitting), I found the check ball more or less wedged on the end of the street ell:



Stuck to the end of the ell like this, it was very effective in preventing backflow to the tank, but it was nearly equally effective in preventing forward flow as well.  This is the actual ball seat, where the ball *should* have been resting (the cage and spring that would go over it have been removed):



I was able to get the ball off its perch, clean it up, and put it back on it's seat with the spring and cage over it. The spring is a bit sloppy and I stretched it a bit to fit; Davco makes a "check valve service kit" that includes a new ball, spring, and cage, and the buyer should probably service this soon, but for now it is working mostly as intended. I suspect the damage to the ball means it will leak down over time.

I'm scratching my head as to how this could happen. I'm thinking that perhaps a day with a large temperature swing caused the fuel pressure in the bowl to rise just as the orifice expanded, thus pushing the somewhat malleable ball back past its seat and out the housing orifice. I'm sure I'll never know, but it's one of the weirder failure modes I've seen over the years.

Once I had the ball/spring check valve back to mostly normal, the engine fired right up and ran normally. It's quite possible that, had I discovered this obstruction earlier, I might have gotten the beast primed and running without replacing the fuel pump. Then again, I could not get it running even with the Davco bowl full and the top cap open, so clearly the lift pump was tired if not finished.

I am very relieved to be past this particular hiccup, and I am grateful to the folks here who helped steer me in the right direction. It's been a long three days.

-Sean

Sean,

You are the Clint Eastwood of busnuts. 

Im truly inspired by your  ingenuity and tenacity to solve problems.

Sad to see you leave the bus world.  You will be missed.

-Sean

[Scott & Heather]

Ditto the above post.


Sent from my iPhone using Tapatalk

[Sean]

Thanks everyone.

And now for today's disappointment: The buyer emailed me over night; his dad passed away last night. I suspect this means the deal is off, but at the very least it means he's not going to have the bandwidth to even think about it for at least a week if not longer. It seems we will be leaving Virginia with the bus unsold.

If I dig far enough into my files I know there were a couple of "call if it falls through" lookers, and we're going to see if any of those can make it out here in the next, say, 27 hours or so; it would be worthwhile delaying our return trip another day if it means I won't have to come back here again later.

It's always something.

Anyone want a nice bus with a brand new fuel pump and fresh filters? It's clean and ready to go 

-Sean

[bigred]

Boy!!! Sometimes you just can't win!!!As a matter of fact ,when it comes to buses ,you will never win the war!! Best you can hope for is to win a small battle every ten years or so !!!lol