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J

jbuffalo

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1978 Mg Midget 1500. New Weber Dgv, Has electric fuel pump, and Holley pressure regulator-(pressure 2.5) have not been able to get it to run right. Just put on new gaskets and the nuts are all tight,new sparkplugs. It started and ran yesterday and I thought it was fixed but now will not start. There is spark, it is getting gas-maybe too much. Could the cylinders be full of gas, changed oil-gas in oil. I have been trying to get this car running for several months-need a little help. thanks Jim
 
You say that you have a Weber and you had it running yesterday? How much of a temperature change has there been between when it was running and now?
 
If its flooding a lot on the DGV, I suggest changing out the float. Go to advance and get one for a 71 pinto. Floats are cheap and a bad one can cause all kinds of problems. If you think it is flooded, pull the breather and verify that the choke is off then hold the gas pedal to the floor and then grind on it and see if it starts.
 
If youve got Gas in the oil than you do have a flooding issue. Is the oil real thin and watery? How are you sure? You say this is new, I once had a similar problem after doing all the work on my weber dg. Turned out little bits of rubber forced there way up into the needle seat from putting all the lines in. May be your problem. Does it smell like its loading up when you crank it? Pull the plugs- are they wet? Look at that float and needle first for sure.
 
If that float is bad, it won't always float up tight and keep the needle in the seat from letting fuel in and it will overfill the bowl and leak down into the manifold. I'm not saying that is it but I see you have gotten a pressure regulator and this leads me to believe that you have something going on like that. Floats don't come in carb kits.
 
Four bolts and off... If the manifold is WET under th' carb, the float is FUBAR.
 
+ like regularman said check the choke butterfly plates. Mine lock closed all the time when there is a slight backfire (more of a carb pop) and in the cockpit the handle will show the choke is off. I fact it just happened to me 3 times today. :frown: I gotta get that fixed.
 
Thanks guys-I will look into the carb in the next few days. The manifold has been wet-gas- when the carb is off. The carb is only 3 months old with few miles. Jim
 
I took the carb off and the manifold was full of gas-I removed the gas. . I cleaned out the float valve-looked ok, and cleaned out everything else with low air pressure. I did not have good directions on how to set the floats, also did not see anything wrong with the floats. One of the bottom butterfly valves was only opening a little(it did not open all the way with the other valve) when the linkage is turned -but I did not know how to set this. Put it on and it started right up and ran well for about 1 minute-then it stopped and would not start. So I know it is the carb--but what? thanks Jim
 
Hi Jim,

There have been a few discussions on this, but... According to Weber, their pumps like / need high volume, and low but consistant pressure. Some have suggested that the mech fuel pump / fuel pressure regulator is not the best solution. I'm not entirely sure I follow that, since liquid isn't (really) compressible and flow is just a function of pressure and tube diameter... I guess what they might mean is that a rotary vane pump is more able to vary its flow, where a mechanical pump's output varies directly with RPM, and then needs to be choked off with a regulator?

FWIW, I'm running a stock pump with the same regulator as you, but have ordered a Carter 4070 (low-pressure electric rotary) fuel pump, to be run without a regulator.

A little reading on the topic.

I'm going to try to get mine running nicely with the stock pump and regulator, before switching over to the Carter. I'll post my results, but please let us know what happens with yours!
 
google pierce manifolds and read all the info on that carb. Shake the float. does it sound like there is any fluid in it. If you spend a bit of time googling weber dgv you will find volumes on how to set that thing up. But I like pierces site the best. A jet may have backed out or be completley missing? More than likely there is something wrong with that float or needle or setting.

here's the link to pierce. https://www.piercemanifolds.com/tech_spec.htm

They do not reccomend any higher than 3psi fuel pressure on that carb either. That can also be some of the problem. Most weber kits recommend installing a QUALITY pressure regulator like a Holley or Summits holley knockoff. (Not the small disc ones from your local parts store as these have been known to fail)
 
Have an electric low pressure fuel pump with Holley regulator, fuel pressure is about 2.5. This weber and manifold is only a few months old and about 10 miles on it, purchased from one of the top British suppliers. The float did not have any fuel in it. I think either the float is off or- and that bottom butterfly valve is not opening right. Thanks for all the information. Jim
 
The car should idle even if the bottom butterfly isn't working. The idle port is actually below that butterfly. There is a transition port just above that butterfly. What I would do is make sure the float height is set correctly.

https://www.piercemanifolds.com/Float_Level_1.htm

This will tell you where to set the float. It might not hurt to set it just a little lower than what they say. Then I would go back to the baseline settings on the carb. 1 1/2 turns on the idle screw (speed) and 2 turns on the idle mixture screw. Go through the lean best idle procedure to make sure that the carb is setup right. You should be able to get this engine to run (if not efficiently but at least it will run) with that carb and those settings. If you uncover the idle transition port with the butterfly (too many turns in on the idle screw) you will be out of the idle circuit and into the main circuit making the adjustments seem less effective.

Hope this helps,
JC
 
Thank you -thank you! It is fixed--it works. The float level was way off on both ends. It starts and runs just like it should. I have spent many hours on this. These were the problems fixed. There were manifold leaks, I put in a new gasket and used Hylomar( bought on Amazon.com)then I gained many skills(manual and verbal) with the two nuts under the manifold-and made a couple of special open end wrenches. A new manifold to carb gasket put in, this one was not as thick as the old one. I now have a British car that runs-- Jim
 
And that is a joy for sure.
 
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