Topic: Fuel pump mystery - 1977 Winnebago D23C Chieftain

[tschotland]

Hi, I am attempting to install a new fuel pump on a 440 engine in a 1977 Winnebago D23C Chieftain.  Push rod is up and out of the way.  I find that if I simpy slip the pump into place, the actuating arm ends up sitting above the push rod entirely.  In order to get it under the tip of the pushrod, I have to angle it in, and then the pump is not aligned with the mounting holes in the block.  It's nearly an inch too low, and angled away from the block.  I have to fight against the spring inside the pump to move it up and into place, and even with all my strength I can barely budge it.  I was worried my pump was broken so I ordered a second one but it is just as hard to move.  What's the trick here?  I have read forums and watched videos but I have yet to see anyone mention this problem.  I have attached a picture of my pump - the cardboard thingy next to it is a mockup of the pump I made so I could look inside the engine and confirm that the actuator arm really doesn't get anywhere near the pushrod.  The string is there to fish the cardboard actuator piece out of the engine in case it happens to break off.  Thanks in advance!

[tschotland]

Never mind.  Problem solved.  There is a Carter pump (model M4589) that has a downward sloping actuator.  That should do the trick.

[tschotland]

Disregard - Carter says that pump M4589 does not cross with the OEM part number (MS-6775, from the service guide).  Thing is, the service guide says Carter made the MS-6775!  And now they have nothing to replace it.

Can anyone recommend a part number that works for this application (1977 Chieftain D23C with 440-3 engine)?

[Eyez Open]

https://moparforums.com/forums/f62/440-3-engine-4973/

http://440source.com/

[tschotland]

Thanks for the links, but the thread you referenced doesn't talk about fuel pumps at all, and 440source.com doesn't have any for sale.

Does anyone have a gph flow rate spec for an appropriate fuel pump?  The service guide only gives a pressure spec in psi.

[Eyez Open]

What type of carb

Below is a video of a guy changing the fuel pump, 440 in a RV. Maybe you might get lucky, several times he video the parts number on the box

https://youtu.be/c5Os5_mXNq8

[tschotland]

Per the service manual, the carb is a Carter Thermo-Quad TQ-6545S.

I've seen that video.  That Car Quest pump is for a B300, which is a van - a much lighter vehicle.  When I spoke with Carter pumps, they said they make many pumps for the 440 engine, the choice depends on the application.  Pressure, flow rate and arm angle can all vary depending on that.  They asked me exactly which Winnebago it was for, then said they had nothing suitable.  So I suspect the guy in the video was sold a pump for a different use of the 440 engine.

[Elandan2]

The correct Carter fuel pump for a 440 is M6935.
Here is the page from Rock Auto: https://www.rockauto.com/en/moreinfo.php?pk=296149&cc=1092338&pt=6256&jsn=960

[tschotland]

I don't mean to be a PITA, but why do you think that pump is okay for the 1977 Chieftain D23C I am working on?  I looked at the page you linked and it says that pump is for a Dodge M300 from 1974.  My 1977 manual says the M300 uses the 360 engine, not the 440.  Also, Carter specifically states that while they make numerous pumps for the 440, they don't make one for this vehicle. 

[tschotland]

So elsewhere in the manual it tells me some M300s do have the 440 engine...love it.

I am not at the vehicle at the moment, but I believe it's an M400 chassis.  That's not listed as one of the vehicles compatible with the M6935 pump.

I could back into a suitable pump by calculating a gph figure.  This page tells you how and gives some guidelines, but the calculation requires knowing the engine's peak horsepower, which of course I don't know:

https://help.summitracing.com/app/answers/detail/a_id/5245

My reading suggests 375 to 400 HP is a reasonable figure.  If that's the case, the flow rate spec is 31 to 33 gph, and the manual says the original pump's pressure rating was 6 psi.  The M6935 delivers 29 gph at 2 psi so maybe that's a bit low - plus I don't have a flow rate vs pressure curve to see how much less it delivers at 6 psi.

Does this match anyone's experience or knowledge?  I've heard if the flow rate is too high, it will flood the carb. That same article says with an appropriate flow regulator there is no harm in having an over-speced pump.  So I need to see if there is one on this engine.

I am treading water in a sea of my own ignorance!   

[Eyez Open]

What mfg and model number is this carb? Rochesters are a bit snippy above 6 psi..Maybe 7 if your lucky

[Elandan2]

All 440's use the same fuel pump.
https://carterengineered.com/find-parts?find=us-car-truck-1975-dodge-d300-fuel-pumps-7-2l-v8-415828813&title=%221975%20Dodge%20D300%20Fuel%20Pumps%207.2L%20V8%22

[DaveVA78Chieftain]

First when searching for chassis parts look under Dodge, not Winnebago. Dodge chassis was used on many brands of RVs so parts are listed under Dodge (M300, M400, M500, etc.)
440-3 engine distributor is in the front of the engine
318 & 360 engine distributor is in the rear of the engine

From the 1977 Dodge Motorhome Parts book:
All 69-77 440-3 engines used the same fuel pump (Dodge P/N 3780113; crosses to Carter P/N M6935)
All 69-77 318 & 360 engines used the same fuel pump (Dodge P/N 3744806; crosses to Carter P/N M60514)

Note: Don't get confused by the fact that the Dodge 360 pickups used Carter P/N M6866 fuel pump

The 440-3 fuel pump pushrod has to be fully pushed back up into it's cylinder.  It has a nasty habit of falling back down while trying to insert the pump in place. You may have to use wheel bearing grease to keep the pushrod in place while installing the pump.  Also you may have to bump the engine to get the pushrod off the high lobe (max retraction of the rod).

[Oz]

Use the VIN Dodge VIN decoder on the main nav bar above.  That will tell you what engine it was built with.  Compare with Dave's visual description and you will know if it's the original or if it's been replaced.

[tschotland]

Hi Dave,

Thanks.  Don't know if you remember me, I started a thread last November on this RV, which I described as having been rewired by Satan himself.  I solved the electrical problems and got the vehicle running again, except for this stupid fuel pump issue.  I have long ago decoded my VIN.  It has a 440-3 engine per the VIN.

I do look under Dodge, the problem is none of the places I looked say that the pumps are compatible with an M400.  Plus I called Carter Fuel Pumps since they made the original pump mentioned in the service manual (MS-6775) and they said they make nothing currently for this RV. 

Now you have pointed me to the Parts book, which I purchased.  It's great that this book lists a completely different part number from the service manual... 

FWIW I spoke to a couple of old salt RV mechanics at Winnebago dealerships who worked on these vehicles when they were new and even then they tell me that there was more than one fuel pump you had to use, depending on the engine ID.  They suggested that I get that info along with the VIN and contact Dodge/Chrysler and also Winnebago.

But now we enter a whole new level of weird.  Attached is the engine ID info I found. I looked in the service manual and saw that it did not match the format to be expected for a 1977 440 engine.

Now I know why: this ID is for a 413 engine.  Winnebago did not make RVs with this engine after 1974.  The ID says this engine was made in 1972.  Also the manufacturing info says it was made during the 3rd shift of the 24th day of a non-existent month.

I have been consulting the 1977 manual for the wrong engine this entire time!  The parts manual shows a different fuel pump is needed for it.

This vehicle does not need a mechanic.  It needs an exorcist.

[Oz]

This vehicle does not need a mechanic.  It needs an exorcist.

 

[DaveVA78Chieftain]

Bummer that sucks

Easiest way to tell a 413 from a 440 RV engine is by spark plug location

You access a 413 spark plug from above the exhaust manifold:
https://www.forabodiesonly.com/mopar/attachments/ramcharger068-jpg.1715061323/

You access a 440 spark plug from below the exhaust manifold:
https://www.forcbodiesonly.com/mopar-forum/attachments/20211125_120930-jpg.499047/

All 69-73 413 engines used the same fuel pump (Dodge P/N 3004107; crosses to Carter P/N M4434)

[Elandan2]

So now the mystery begins to unfold!! The previous owner obviously replaced the 440 with a 413. That would explain all the wiring changes, 413's didn't have electronic ignition so the wiring was adapted to work with a point ignition. Carter lists the pump as model M6191 for the 413. It is the same pump as the M6935 with different inlet and outlet. The M6935 pump will work, but you may have to modify the fuel lines.