DMCH fuel pump/sender combo won't quite fit into tank opening

[jangell]

I've cleaned out the tank as best I could (acetone, rags-on-a-stick to try to reach the back of the tank, blindly waving around a shop vac to get the loose bits), and finally tried to install my DMCH fuel pump/sender combo .

What I found is that the pump will not fit I put leave the rubber gasket on it while I insert it into the tank. I have to mount the gasket in the tank opening first, and then I can push the pump into the hole and gasket. However, I can't actually get it to push down as flush as the pictures shown in the installation instructions. I tried quite a lot of force (without damaging the plastic pump housing -- I nearly stood on top of it), but I was actually flexing the top of the tank, and not moving the pump. It seemed to be in there pretty tight, so much so that I cannot rotate the pump once it is in there (as the instructions say to do to line it up), even without the clamp tightened.

I've attached a picture showing the gap between the clamp and the pump. The clamp is positioned as per the instructions in this thread (http://dmctalk.org/showthread.php?7849-DMCH-Fuel-Pump-Sender-Combo-Installation-Video) and this thread (http://dmctalk.org/showthread.php?3824-NEW-Integrated-pump-sender-combo!/page9), ensuring that the clamp sits over the edge of the white plastic to hold it down.

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Note that the pump is not sitting at an angle; that's just shadowing from how the light is positioned.

I'm mostly concerned that I simply don't have the pump far enough into the tank, but I don''t know how I could possibly get it in any further. I did try to tighten the clamp, although I'm a bit worried that it's just clamped onto the seal and not to the lip of the tank, and thus won't actually be holding the pump to the tank. I can't actually see if the clamp is on the lip or not; I suppose I could measure to the top of the lip and see how low it's supposed to sit...

I did test fit the access cover, and it seems to clear the pump with no problems, so I don't think that'll be an issue. I just don't want the seal to be bad and get water in the tank again.

Thanks!

-- Joe

[DMCMW Dave]

Pull it back out and make sure that the springy assembly is working all the way. You should be able to press that much further than required to seal the tank. Make sure you haven't trapped something under it.

[Silverbullet]

If you remove the clamp you can see if the Black lip of the rubber is resting on the lip of the tank as it should, and the White lip needs to rest on top of the Black Rubber lip.

[jangell]

Pull it back out and make sure that the springy assembly is working all the way. You should be able to press that much further than required to seal the tank. Make sure you haven't trapped something under it.

I did confirm the spring assembly was working correctly before I tried to install it; it seems to operate smoothly and easily.

You should be able to get the pump into the tank with the rubber gasket already installed on the pump, right? I couldn't -- it just wouldn't fit.

At this point I'm wondering if my tank's opening is simply slightly smaller than normal. I'll have to measure it. I am considering taking some sand paper to the edge (and then cleaning the tank out again, yay) and seeing if that helps. I have an early VIN car (767), but I have trouble believing that the fuel tanks are different on the later cars.

-- Joe

[jangell]

If you remove the clamp you can see if the Black lip of the rubber is resting on the lip of the tank as it should, and the White lip needs to rest on top of the Black Rubber lip.

I'll have to try that again. I couldn't see how to completely remove the clamp while the pump was in the tank, as the hose connections were in the way. I'll have to see how far I can take the nut off to widen the clamp.

I should have some time to play with it again on Tuesday morning and report back. At the very least you've both proved that it is not seated properly and that I need to work on it some more. Thanks!

-- Joe

[DMCMW Dave]

At this point I'm wondering if my tank's opening is simply slightly smaller than normal. I'll have to measure it. I am considering taking some sand paper to the edge (and then cleaning the tank out again, yay) and seeing if that helps. I have an early VIN car (767), but I have trouble believing that the fuel tanks are different on the later cars.

-- Joe

Actually I was told by a reliable source (Stephen Wynne) that there are three different moldings of the gas tank used during production, although I don't know what the differences were. That seems like the kind of dimension that may have changed for ease of assembly.

[jangell]

Actually I was told by a reliable source (Stephen Wynne) that there are three different moldings of the gas tank used during production, although I don't know what the differences were. That seems like the kind of dimension that may have changed for ease of assembly.

Ah, very interesting. Perhaps this also explains why I couldn't quite fit my arm all the way in the tank as some other people seem to have been able to do. Or I just need smaller arms.

I have no problem taking sand paper to the edge of the tank to try to widen it. I get the impression that the fuel pump with gasket should slide into the tank with some friction, but shouldn't need to be forced. Should there be enough friction to hold the pump down before the clamp is tightened, or will it spring back up without the clamp? That should give me some idea of how wide the hole should be for access.

Thanks!

-- Joe

[WelmoedJ]

Ah, very interesting. Perhaps this also explains why I couldn't quite fit my arm all the way in the tank as some other people seem to have been able to do. Or I just need smaller arms.

I have no problem taking sand paper to the edge of the tank to try to widen it. I get the impression that the fuel pump with gasket should slide into the tank with some friction, but shouldn't need to be forced. Should there be enough friction to hold the pump down before the clamp is tightened, or will it spring back up without the clamp? That should give me some idea of how wide the hole should be for access.

Thanks!

-- Joe

Arms and tank openings have there own "diameter".
Indeed the tank opening may differ slightly as I found in my previous and current D.
The new SS three legged boot bracket (Hervey's) that I installed in the previous D slipped in without any force.
I had to use a hammer to make the same bracket fit the current D.

BTW: If your arm's diameter (near the shoulder) is a bit oversized compared to that of the tank opening, you could try and borrow someone else's arm (perhaps a woman's arm?).

[DMCMW Dave]

. Should there be enough friction to hold the pump down before the clamp is tightened,


-- Joe

Yes, at least for a short time. It should not be hart to seat the rubber against the upper lip, but it may take slight pressure. You should not have to beat on it.

[virtualchuck]

Yes, at least for a short time. It should not be hart to seat the rubber against the upper lip, but it may take slight pressure. You should not have to beat on it.

I had a similar issue with the tank and/or the pump sender I installed a couple of weeks ago. Work the springs a few times times before you try to install it, and I also found that it will only sit properly if you wiggle it around a little and even have it at a slight angle (towards the driver's side) while clamping it (It felt like there was a slight hump in the fuel tank?). It also doesn't hurt to have someone else pushing as you tighten.

Chuck

[jangell]

Arms and tank openings have there own "diameter".
Indeed the tank opening may differ slightly as I found in my previous and current D.
The new SS three legged boot bracket (Hervey's) that I installed in the previous D slipped in without any force.
I had to use a hammer to make the same bracket fit the current D.

For some reason I didn't think of a rubber mallet or a block of wood and a hammer, but I am worried about breaking the plastic body of the pump. The fact that I was flexing the tank instead of pushing the pump in when I was nearly standing on it implies that a hammer might not help, although the shock of a hammer is different from the constant force of standing on it.


BTW: If your arm's diameter (near the shoulder) is a bit oversized compared to that of the tank opening, you could try and borrow someone else's arm (perhaps a woman's arm?).

Unfortunately, I'm a bit of a recluse, and my wife has nerve damage in her arms and won't be able to help, so it's pretty much just me. I'm pretty sure the tank is adequately clean, though. Or at least I'm willing to risk it.

-- Joe

[jangell]

Yes, at least for a short time. It should not be hart to seat the rubber against the upper lip, but it may take slight pressure. You should not have to beat on it.

Thanks -- that gives me a good idea of how much to sand to widen the opening. It feels like it's just a bit too tight, and that there's enough of a lip on the tank that I can sand it wider without compromising it.

-- Joe

[jangell]

I had a similar issue with the tank and/or the pump sender I installed a couple of weeks ago. Work the springs a few times times before you try to install it

I did play with the springs fair bit, first because I thought it was an interesting design, and then when I was fighting to get the just-a-bit-too-small hose clamps on the hose over the snap-on barb fittings on the pump before I realized that I could unclip the fittings. They seem to operate pretty smoothly, and work fine when I removed it from the tank. I think this is more of an issue of the size of the opening vs. the size of the part of the pump that sits in the opening on my particular car. I'll measure on Tuesday morning before I try sanding it a bit wider.


and I also found that it will only sit properly if you wiggle it around a little and even have it at a slight angle (towards the driver's side) while clamping it (It felt like there was a slight hump in the fuel tank?).

That's interesting. There is the stud that the old baffle was mounted on; I had been wondering if that would get in the way. Perhaps that's the hump you were noticing? I had been considering cutting it off with a Dremel, but I wasn't sure if it was actually in the way or not, and no one else seemed to mention anything about it...

Thanks!

-- Joe

[DeMopar]

I did play with the springs fair bit, first because I thought it was an interesting design, and then when I was fighting to get the just-a-bit-too-small hose clamps on the hose over the snap-on barb fittings on the pump before I realized that I could unclip the fittings. They seem to operate pretty smoothly, and work fine when I removed it from the tank. I think this is more of an issue of the size of the opening vs. the size of the part of the pump that sits in the opening on my particular car. I'll measure on Tuesday morning before I try sanding it a bit wider.



That's interesting. There is the stud that the old baffle was mounted on; I had been wondering if that would get in the way. Perhaps that's the hump you were noticing? I had been considering cutting it off with a Dremel, but I wasn't sure if it was actually in the way or not, and no one else seemed to mention anything about it...

Thanks!

-- Joe


The stud should be offset so that the pump will clear it, and I wouldn't cut it unless you determine that you absolutely have to. I wonder if the stud might be in a different location being such an early vin?

[jangell]

Good question. I have a picture of the tank and the stud location, but this was not taken from directly above.

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It looks like it's reasonably off-center. Since there was no mention of it in the docs, I assumed it wouldn't be an issue. I'd rather not cut it off if I don't have to.

-- Joe

[DeloreanJoshQ]

If it will help, Version 2 of the fuel pump/sender install with all of the corrections made:
http://youtu.be/W2vaigaomog

[DMCMW Dave]

If you orient the pump as shown in the instructions the stud is not in the way. If you try to put it in facing a different direction, it would hit the stud. You'd also find that the hoses would hit the cover, or the float would hit the side of the tank, so it really only goes in one way.

[Silverbullet]

If it will help, Version 2 of the fuel pump/sender install with all of the corrections made:
http://youtu.be/W2vaigaomog

Great job on the video, it should help a lot of people.

Craig

[kings1527]

Great job on the video, it should help a lot of people.

Craig

+1. I wish I saw that before I did mine. Nice work!

[virtualchuck]

If it will help, Version 2 of the fuel pump/sender install with all of the corrections made:
http://youtu.be/W2vaigaomog

Thanks for the video Josh. While we're on the topic, can anyone tell me where the ground that is attached to this harness goes?

Chuck

[jangell]

I think I was overly concerned about getting the top of the pump flush with the the top of the tank. I think my car's tank has an unusually high lip around the opening, and that it actually WAS seated properly.

I did first actually try to sand down and then slowly Dremel down the opening of the tank, with a garbage bag in the tank to catch most of the shavings; that got old fast, and did barely anything.

I wound up removing the rubber boot from the pump, mounting that in the opening, and squeezing the pump through the boot and into the tank. The bottom part was pretty tricky, and I had to remove the rods that linked the top and bottom of the pump to clear the lip of the trunk, and then re-insert them inside the tank (I'm going to check again through the sender cap this weekend to make sure both really are in place correctly; in retrospect, I think I may have missed one).

After that, I pushed the pump down as far as I could, with the clamp out of the way enough that I could see the interface between the pump and the tank. It looks like it's sitting pretty flush, more so than you can see in the pictures (messing with the clamp for more visibility for the photos shifted the pump a bit, but afterward I hammered on a piece of wood placed on the top of the pump to ensure it was as tight as it could get).

When I tightened the clamp, I confirmed that it is gripping the tank properly -- when I tried to pull it upward, the entire top of the tank would flex. So I think I'm good.

Note that in some of these pictures that clamp is lifted up and out of the way to more clearly see where the rubber boot meets the tank opening; in the finally assembly, the clamp is gripping the tank.

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The last picture shows a bit of a kink in the return line. I'm thinking that it's probably fine; it's not a lot of kink, and the rubber hose is a large diameter than the metal fuel line anyway (I think), so I don't think the flow is constrained. I'm trying to decide if I want to undo the clamp and pry out the fuel pump enough to rotate it.

I also realize the hose clamp on the return line is further down than I'd like, but it is definitely gripping the barb (I couldn't pull it off no matter how much I tried). I may put a slightly larger hose clamp on there anyway, just to be sure; the ones included with the kit barely fit over the rubber hose when they're not on mounted on the snap fittings, and when they're expanded by the barb it's even harder to slide them (although using an adjustable wrench for more leverage did help).

I didn't try to start the car yet; I'm going to replace the fuel filter this weekend, but I don't expect any problems with the pump (getting the fuel filter off, on the other hand...)

Thanks everyone!

-- Joe

[jangell]

If it will help, Version 2 of the fuel pump/sender install with all of the corrections made:
http://youtu.be/W2vaigaomog

Thanks for the video -- I looked at the original before I installed my pump; I'm sure I would have put the clamp in wrong if not for the thread and your update.

-- Joe

[NightFlyer]

No problems with my install of the unit - I just followed the provided instructions to the proverbial 't' and things went great!

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