Hot Starting Issues

[55 Fargo]

Post deleted

Edited March 7, 2014 by Fargos-Go-Far

[jeffsunzeri]

An electric fuel pump may overwhelm the float and needle assembly if the pressure is not regulated to a low enough value. That excess pressure at shut down would account for the strong fuel smell and the hard starting.

[Jerry Roberts]

An electric fuel pump may overwhelm the float and needle assembly if the pressure is not regulated to a low enough value. That excess pressure at shut down would account for the strong fuel smell and the hard starting.

 That is a good point . I have a separate switch for my electric fuel pump and I always turn off the pump a few seconds before I turn off the engine .  

[Jeff Balazs]

I have a separate switch for my fuel pump as well. One thing I have not done is a pressure test. I have a rotor style pump which is not supposed to be able to exceed 5 3/4# but I should probably check it.

 

I got the infrared gauge yesterday and it is supposed to be in the low 80s on Saturday so I should be able to start taking readings.

Should be interesting to see what is actually happening with the temps at the float bowl.

 

Jeff

[55 Fargo]

Post deleted.

Edited March 7, 2014 by Fargos-Go-Far

[HanksB3B]

In this diagram, it looks like there is an insulator (14-33-5) between the 2 bodies.

 

Are you saying Jeff doesn't have one ?

 

Hank 

[Jeff Balazs]

Are you saying Jeff doesn't have one ?

 

Hank 

It is in place.....I believe it is an intregal part of all DT B & B carbs and has to be in place in order for them to function properly.

I will update this post with my findings after I have taken enough readings to make sense of things.

Jeff

[T120]

I have a separate switch for my fuel pump as well. One thing I have not done is a pressure test. I have a rotor style pump which is not supposed to be able to exceed 5 3/4# but I should probably check it.

Jeff

 

First I should mention,I have the stock mechanical fuel pump and carburetor in my '48 Dodge D25.I haven't had a problem with "vapor lock" as yet.

My shop manual says the pressure at the carb inlet should be 3 to 4.5 lbs on my Dodge...(I had a '54 Lincoln Capri some years back with a 4 barrel Holley - the specs on the fuel pressure at the carb inlet on that was 3.5 to 4.5 lbs).If I had an electric pump installed with a stock carburetor,I don't think I would exceed 4 lbs. jmho

[Jeff Balazs]

First I should mention,I have the stock mechanical fuel pump and carburetor in my '48 Dodge D25.I haven't had a problem with "vapor lock" as yet.

My shop manual says the pressure at the carb inlet should be 3 to 4.5 lbs on my Dodge...(I had a '54 Lincoln Capri some years back with a 4 barrel Holley - the specs on the fuel pressure at the carb inlet on that was 3.5 to 4.5 lbs).If I had an electric pump installed with a stock carburetor,I don't think I would exceed 4 lbs. jmho

Thanks Ralph;

I do need to get a pressure reading on this. If it seems too high I can always add a regulator. I don't have my truck manual handy but it seems to me that it allowed for a bit higher pressure than 4.5#. Either way it probably wouldn't hurt to have it regulated to the range you have mentioned.

 

Jeff

[Plymouthy Adams]

_{this is Plymouth car manual I know...but specs for fuel pumps are......4 to 4.5 from 1946 through 1954..}

 

 

_{HOWEVER..from the Motors manual comes this data...}

 

_{Chrylser, Desoto and Dodge   1940 -47   pressure 3 to 4}

_{Plymouth 1940- 46 Pressure 3-4}

_{Chrysler Desoto,  1948-55 pressure 3.5 to 5}

_{Dodge 1948-54 pressure  3.5 - 5}

_{Dodge 1955 is 4.5 -6}

_{Plymouth 1947-52 pressure 3.5 - 5}

_{Plymouth 1953-55 pressure is 4 - 5.5}

Edited March 7, 2014 by Plymouthy Adams

[Don Coatney]

Vapor lock can only happen if the fuel forms bubbles on the suction side of the fuel pump preventing the pump from working. Is everyone now convinced that the problem discussed in this thread is not vapor lock? Pretty much impossible for a mopar flatty to get vapor lock due to the position of the fuel pump in relation to the tank. Vapor lock is reserved for furds with the fuel pump sitting on top of the engine. This has been discussed many times on this forum. And with an electric fuel pump located close to the tank pushing cool fuel to the carburetor how is it possible for the fuel under pressure inside the tubing to vaporize and thus cause the pump to stop pumping?

[Jeff Balazs]

Thanks Don;

I found my B Series truck manual and it says to fit a tee ahead of the carb and it should read 3.5 to 5.5 with the engine running.

I wonder how this translates to what the electric pump can do with the engine off? I have run the pump several times against the float valve with the engine off and have not had any leaks or odor. Just a guess but I suspect this pump probably puts out something in the range of 3.5 to 5 pounds. When I was researching what pump to use as a full time replacement this vane type pump keep being the one that a lot of antique car owners liked the most. I kinda doubt it has anything to do with the hard starting when hot or vapor lock........but I need to be absolutely certain if I am going to find a real fix.

 

Jeff

[TodFitch]

Vapor lock can only happen if the fuel forms bubbles on the suction side of the fuel pump preventing the pump from working. Is everyone now convinced that the problem discussed in this thread is not vapor lock? Pretty much impossible for a mopar flatty to get vapor lock due to the position of the fuel pump in relation to the tank. Vapor lock is reserved for furds with the fuel pump sitting on top of the engine. This has been discussed many times on this forum. And with an electric fuel pump located close to the tank pushing cool fuel to the carburetor how is it possible for the fuel under pressure inside the tubing to vaporize and thus cause the pump to stop pumping?

I agree that the problem listed in this thread is not vapor lock.

 

But I have had vapor lock on my '33. Symptom: Idling after a long hot run on a hot day (above 90°) engine dies. Or, alternatively, same hot day and long hot drive followed by a stop. On restart engine will run for a short while (fuel in float bowl) and then die. Fix, or rather work around in my case, is to pour some water on the fuel pump. Once you do that engine will restart and run okay. One of these days I'll retrofit the fuel pump heat shield that the factory added to later models and I should be good to go. I've got the special fuel pump/heat shield mounting stud but haven't gotten the "round to it" needed to actually get the shield and install it.

 

Now that you mention the level of the fuel pump, I am wondering if my problem is mostly when the tank is low and there is not a lot of gravity assist on the flow to the pump. . . Never correlated that one, I'll have to watch for it. Assuming I don't put the shield on first.

[T120]

Vapor lock may be the wrong term...what I visualize is perhaps that with the engine hot and fuel percolating in the carb, flooding may occur and when the ignition switch is turned on to start the engine the needle valve may not be seating properly,(everything being hot),having fitted an electric fuel pump the carburetor may be hit right away with fuel at a higher than optimal pressure and that may aggravate the problem...just saying,I can't claim this as fact

[Jeff Balazs]

Ok.....I suppose I am guilty of using the wrong term for this problem.

What ever you want to call it....I think it needs to be corrected.

 

Jeff

[Jeff Balazs]

I am going to close this thread out as it is incorrectly titled.

I will start a new thread titled "Hot starting issues" unless someone has a better title? I just want to get to the bottom of what causes this and find a permanent fix.

 

I did spend some time reading through my B series truck manual last night. The factory acknowledge's the possibility of vapor lock as a potential starting problem in the Engine Performance section of the manual on page 282. Under remedies they suggest one checks for air and fuel restrictions around the fuel pump and check for a misplacement of the heat shield. So clearly while I have misused the term.....they were aware of the possibility that the condition could exist.

 

Jeff

[Don Coatney]

Have a moderator change the thread title.

[JBNeal]

Hot Starting Issues solved with fuel line insulator sleeves installed 

[Jeff Balazs]

Hi Brian;

I don't believe that my rerouted fuel line is getting warm at all.

 

One thing I have noticed is the engine is not cold starting as easily now as it did on our summer formulation fuel. It was starting on the first attempt 95% of the time.....now it is taking 3 or 4 attempts. I have a new kit coming for the carb and I will revisit this before I install the insulator/heat shield I have made to go between the carb and the manifold.

 

It is just possible that the heat riser is having a negative effect on this condition. I have been watching it closely and while the spring does get softer when it warms up it does not seem to release enough tension for the flapper to go into the off position at idle. It does move as you would expect when the throttle is applied.

 

Initial readings I have taken with the infrared meter indicate that the temperature of the float bowl is getting up to around 150 after the engine has run for 15 minutes. The manifold at the base of the carb gets over 200 degrees. Air temp for both initial tests has been around 65. By tomorrow it will be in the 80s.

 

Jeff

[jpwuertz]

I had the same had the same hard starting problem when the engine was hot.  I replaced the 180 degree thermostat with a 160 degree and that took care of the problem for me.  I do believe the shop manual states that the thermostat should start to open at 157 degrees.  This will keep the engine temp down after a long drive on a warm day.

[deathbound]

Are you saying Jeff doesn't have one ?

 

Hank 

 

No, just making an observation from the diagram....regarding an insulator on the carb. Looks like it HAS to be installed for it to work properly.

[FN2]

Jeff, you will probably see a very noticeable improvement when you install the heat shield and spacer. I installed one in my inline 6 ford engine in one of my trucks and it completely solved the problem of hard starting when hot. I will follow what results you get and if it works  then I will install a similar system on my Fargo. Very interesting thread.

[Jeff Balazs]

I ran another series of temperature reading today around noon. Low 80's and very low humidity. No big surprises.......the temps were a fair bit higher. 10 minutes after shut down I could smell gas. Not super strong..... but enough to know that something is going on. I need to find some fittings to test the fuel pressure. I now have a fresh carb kit and will remove the carb to check conditions and float level before making any other changes.

 

I removed the standard fan and fitted a 6V pusher last year. It certainly is a lot quieter but with the warmer conditions it seems to struggle keeping the temperature down at idle after 10 to 15 minutes. I know this isn't a condition that the truck will see that often but it does get a lot warmer here. I am a bit concerned about this fan not being adequate for stop and go conditions in really hot weather. I have pulled the 180 degree thermostat I had in the truck about a month ago and fitted a new 160 one when I flushed the radiator. The radiator tank temperature today was almost 20 degrees higher than it was when I tested it early yesterday morning. Same running time.

 

Thanks for all your suggestions. Will update this as I have time to test.

 

Jeff

[greg g]

next time it happens look to see if there is any raw gas near the throttle plate bushings on the lower portion of the carb If so, follow Todd's recommendations regarding WOT starting procedure and float setting. Difficult Hot start is not a vapor problem it is a raw fuel problem.

Edited March 9, 2014 by greg g

[T120]

You might check out this thread from a while back..Interesting reading  

http://p15-d24.com/topic/15128-carb-heat-shield/?hl=%2Bheat+%2Bshield

- also this, http://p15-d24.com/topic/12547-fuel-pressure-regulator-project/?hl=%2Bpressure+%2Bregulator

Edited March 9, 2014 by Ralph D25cpe