Snake pit - rhino built

[Rhino13]

Good to know. So seeing as I have a Weber without an idle cutoff solenoid, would it make sense to take that one out and leave the one that deals with the plugs? And if so should I cap it or unplug it from the harness?

[Rhino13]

Well I think my fairly new fuel pump is going out, but I thought I'd see what you guys have to say.

 

I put the Weber on the truck and when it gets fuel, it will run good, but usually only runs for 10-20 seconds then stalls. I have the mixture screw 2 1/2 turns out, and earlier today after it started a few times briefly then wouldn't start anymore, it was still spraying gas out of the jets. I removed the gas line into to carb and it was pretty low pressure, but managed to fill the bowl briefly. My fuel pump was hard wired into the red wire on the circular plug for the stock carb. I put it in the red with a yellow stripe and cleaned it up and it seemed to get more pressure, but still not enough. Are either of those sufficient to power the fuel pump? And if not, where is a good place to splice into? It has a 15amp inline fuse also.

[datzenmike]

The stock pump should be more than enough. Check for anything that would cause resistance to flow... like a dirty fuel filter (maybe installed backwards?) There is a filter between the tank and the electric pump to protect it. There is also a filter and a magnet in the bottom of the stock electric pump. The cover just twists off by hand. Are the fuel lines clean or full of rust? Is your fuel return line working, it should be for best results. Is the weber float set correctly. Too low and it can run empty faster than it can be filled. Is there dirt blocking the needle valve at the inlet to the carb?

[denmarkboy]

Hit me up , I will be all over town today . I could come by and smack it around some for ya ...

[denmarkboy]

  So pickup Rhino this morning (way before it got hot ) and gave this baby a once over , so this carb  needs to come back off , Tom at brooks let us dig thru some tubing and fittings , should be able to fix the vacuum advance piece that is missing , and the fuel pump is way over powering the carb . It must be pushing 7+ pounds of pressure , 

 

Did get it running and driving , but it neds those things fixed , and a tune up . It hasnt had one of those in a long time . but after those issues are addressed it should run pretty good . 

 

and the pics .  .  .

 

[Rhino13]

Yeah we got it to run a bit, still needs a few things like Al said but it's getting there.

 

It seems weird to me that the fuel pump is too much for the Weber, but ran fine with the stock carb. Once I try to drive it, even after we got it to idle yesterday, it just falls on its face and makes the truck shutter unless I feather it up to higher rpms. Even if I have the rpms up, it starts shuttering and sounding like it's missing, and always manages to die. Al got the idle to a good low spot and it sounded like it was missing then too. I plan on getting new plugs, wires, cap, and rotor. Is there anything I should check on?

[Rhino13]

So where is the fuel pump supposed to be wired to? Mine is hard wired to the little round plug that hooked into the stock carb. There is a 15amp fuse inline with it, but could this be part of my problem?

 

Also my webers choke cam was broken, so I'm running it with no choke. I should be able to start it and choke it with my foot until it warms up, right? When Al put his hand over the top with his fingers spread out, it started up and idled but struggled without it. It was warm when we were doing it, so it shouldn't have needed the choke anyway.

[datzenmike]

The electric fuel pump merely supplies fuel to the carb. It has a regulator built in and when the output pressure reaches 3.0 PSI ???w/e, the pump stops or slows down. The carb uses a float and a needle valve. As the fuel is used the float drops and the needle valve opes letting in more fuel. As the float rises, the needle valve closes and stops the fuel getting in. This is self regulating and the level doesn't really drop that much, it just stays close to the same.

 

Now pump output, does not affect how the engine runs at all, unless the carb should run dry or over fill. If the float is set too low you may use gas faster than it can get through the almost closed needle valve and the carb empties and runs out. Likewise if the float is set too high the needle valve can't close the the carb over flows with gas. That's the carbs fault. If a pump is used that produces too much pressure it will force it's way past the needle valve and flood the carb. Or the pump may be too small for the job and can't supply gas fast enough to keep up. This is the pump's fault. Actually it's all the owner's fault.

 

Weber carbs, specially old ones, are very sensitive to too much fuel pressure and often will flood with the stock L series mechanical fuel pumps. They run about 2.8 to 3.8 PSI.    

 

 

Get the choke working! Cold engines don't fully evaporate the fuel even in the summer and run like shit on a lean mixture. Cold engines NEED and over rich mixture (provided by a choke) to run properly until warm enough.

[Rhino13]

The electric fuel pump merely supplies fuel to the carb. It has a regulator built in and when the output pressure reaches 3.0 PSI ???w/e, the pump stops or slows down. The carb uses a float and a needle valve. As the fuel is used the float drops and the needle valve opes letting in more fuel. As the float rises, the needle valve closes and stops the fuel getting in. This is self regulating and the level doesn't really drop that much, it just stays close to the same.

 

Now pump output, does not affect how the engine runs at all, unless the carb should run dry or over fill. If the float is set too low you may use gas faster than it can get through the almost closed needle valve and the carb empties and runs out. Likewise if the float is set too high the needle valve can't close the the carb over flows with gas. That's the carbs fault. If a pump is used that produces too much pressure it will force it's way past the needle valve and flood the carb. Or the pump may be too small for the job and can't supply gas fast enough to keep up. This is the pump's fault. Actually it's all the owner's fault.

 

Weber carbs, specially old ones, are very sensitive to too much fuel pressure and often will flood with the stock L series mechanical fuel pumps. They run about 2.8 to 3.8 PSI.

 

 

Get the choke working! Cold engines don't fully evaporate the fuel even in the summer and run like shit on a lean mixture. Cold engines NEED and over rich mixture (provided by a choke) to run properly until warm enough.

My fuel pump is rated from 3-5.5psi so if anything I need the regulator. It is an old Weber. I thought I set the float right when I rebuilt the carb, but I'll pull it off and see if it maybe got bumped out.

 

I plan to get the choke working, my question was will it run without it? I have every piece of it, the little piece that comes off the choke cam to connect it to the rest of the linkage is broken, so if anyone has a source to new or used Weber parts please let me know.

[Draker]

It will run fine without the choke. But starts will be a bit of a pain until it's warmed up. I'd get a line regulator set it to 3psi and move on to tuning this mofo!

 

Good work man.

[KoHeartsGPA]

Are the jets ok?, that carb may need to be rebuilt, make sure you get new jets in the kit.

[Rhino13]

I am absolutely getting a regulator, I want it to run as well as it can.

 

Tried starting it again today just to see if it happened to start. It tried for a second but then wouldn't start. Changed the fuel filter and the pump can't even pump gas into the filter... So I'm going to replace that tomorrow and hopefully that's all. When my stock pump went it did the EXACT same kind of shuttering, but only from about 35mph+. The pump sounds like it's running, but it's not pumping anything.

[Rhino13]

Are the jets ok?, that carb may need to be rebuilt, make sure you get new jets in the kit.

The jets we're soaked in cleaner for more than a day and looked good before soaking. It was rebuilt the day before being put on so all new hardware.

[datzenmike]

I am absolutely getting a regulator, I want it to run as well as it can.

 

Tried starting it again today just to see if it happened to start. It tried for a second but then wouldn't start. Changed the fuel filter and the pump can't even pump gas into the filter... So I'm going to replace that tomorrow and hopefully that's all. When my stock pump went it did the EXACT same kind of shuttering, but only from about 35mph+. The pump sounds like it's running, but it's not pumping anything.

 

If the pump won't fill the filter maybe the lines have sediment blocking them. A stone may have hit the line and pinched it. Also place a filter before the pump to keep any crap out of it.

[Brohemius]

The filter he is refering to is indeed behind the pump, i thought it might be some fuel line blockage also. But it really seems like the pump just cant pull fuel, the filter he just replaced seems totally fine and clog free. Its gotta be the pump.

[datzenmike]

...or the line forward of the pump to the carb?

 

Funny thing about pumps, even a thousand HP diesel pump can't suck water up much more than 30 feet yet pressure is almost unlimited.

[Draker]

I have a new low pressure pump you could have.

[Rhino13]

Whats the pressure rating on your pump Craig?

 

Is there a good way to clean the hard lines if that's where the clog is? There's only one small section of hose that hasn't been replaced.

The main reason I think it's the pump is because it started acting the same as it is now, but with my old carb and vacuum lines seemed to temporarily fix that problem. Then the carb came off and Weber went on, now its acting the same, although it did fill the float bowl a few times, it quickly ran out of fuel then wouldn't start again.

I'm going to start with checking all the lines, then change pump and get a regulator if they're not clogged. Thanks for the help

[datzenmike]

Pumps can't suck for shit but they can pump very well. There can be no restriction on the suck side. Mount pump as low as possible and as close as possible to the tank to reduce it's work sucking fuel.

[Rhino13]

The pump is in the same place it was when I installed it, and it had no problems getting fuel immediately when I changed the filter then.

[Lockleaf]

The location could be causing your pumps to be short lived however. The stock location is very close to the tank and hung low as possible on the frame. You noted that your pump is wired to the old carb connector. Does this mean your pump is in the engine bay? If so, it's too high, it's too hot and it's too far from the tank, all of which can cause problems and shorten pump life. If it's not basically where Nissan would have put it, move it.

[Rhino13]

It's mounted in the stock location, I may try to shorten the length of lines between the pump and filter, if I remember correctly there's some extra.

[Draker]

Whats the pressure rating on your pump Craig?

Is there a good way to clean the hard lines if that's where the clog is? There's only one small section of hose that hasn't been replaced.

The main reason I think it's the pump is because it started acting the same as it is now, but with my old carb and vacuum lines seemed to temporarily fix that problem. Then the carb came off and Weber went on, now its acting the same, although it did fill the float bowl a few times, it quickly ran out of fuel then wouldn't start again.

I'm going to start with checking all the lines, then change pump and get a regulator if they're not clogged. Thanks for the help

Not a 100% sure but it's for a carb. I want to say it's right around 3psi.

[Rhino13]

Well I came to do stuff on the truck but all parts stores are closed. The pump sucked gas into the filter now and if I turn the throttle it sprays fuel into the venturi, so I'm thinking it may just need the regulator. It's so back and forth it's hard to tell what's happening with it.

[Draker]

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