Cold start issues on a Maserati

Sounds like your carbs aren't getting fuel.

This can be a result of:

bad fuel pump/s

clogged filter

some other blockage

Sounds like your pumps run (or at least make noise) so it's not electrical.

Weber carbs typically operate at pretty low fuel pressure (2-4psi) but they won't supply fuel to the engine if their not full.

That glass bowl is actually part of a pressure regulator/filter. One possibility is that the filter element is clogged, another is that the pressure is set too low. When you turn on the key, the glass bowl should fill right up and stay full.

The original Facet pumps on that car typically have their own filter elements built into a removable cap. They could be plugged. There is also probably a "sock" filter on the fuel pickup inside the tank. If the tank has never been cleaned out, it could be a problem.

The pressure gauge is just an accessory that someone installed (maybe because they were having trouble). There should never be 15 psi anywhere in that fuel system. Are you sure it isn't 1.5?

 

I had an 84 qporte and it would fire instantly on key turn better than any car I ever owned. I never understood why. Anyway, I would start by seeing what the output of fuel is aft of the 4 carbs. You can see the flow on the returnline to the tank just after the last carb. There is a wsm spec for that. You can also avoid the long crank by using some starter spray to light off the stored car but then the fuel should be flowing in a properly tuned car and it shold be running fine.

 

If nothing happens when you turn the key on (you should hear it) you likely have a dead pump.

 

Does your car have a mechanical pump? The cars I am familiar with have two electric pumps.

Of course a mechanical pump only works when the engine turns.

 

I think you are right-- the main pump is completely dead and the auxillary is barely functioning.

Webers require something very close to 3.0 psi to operate. Any more than 3.5 or so and you run the risk of fuel overflowing into the intake system, causing rich running. If the engine is off and the pump is running the fuel will run down the intake system and fill a cylinder. Then when you turn the car over you will "hydraulic" a piston and bend a rod.

If there is too little fuel the engine will run lean and possibly burn a piston.

Under the cover nut on that filter / fuel pressure regulator there is a screw or nut (I forget which) that you can turn to adjust the fuel pressure. You should adjust it so it is at 3.0 with the engine at fast idle.

Just went thru all this with my Abarth vintage racer.

 

post picture abarths are cool

 

+1

All the vintage V8 Maseratis should start very easily once you let the carbs fill.
From your description of the symptoms I would go through the above checklist before you start replacing pumps. The facet pumps are easy to get and inexpensive if you buy them from the right places. $80-$90. The secondary backup pump on your car might be something weird or just one of those small solid state pumps.

Typically I let the carbs fill, give the throttle 2 or 3 good stabs and then the car usually starts. I never use the choke.

I might add checking to see if your accelerator pump circuits in the carbs are working. If not then cold starts are going to be difficult. You can look down the top with a flashlight and see that. If not, it might be dirt or quite possibly just a new set of accel. pump diaphragms. That's a relatively easy repair. Your car should also be stumbling or hesitating once under way if the diaphragms are bad.

Bob S.

 

If tha main pump makes no noise with the key on check to see if you have power at the pump. Bad wire or fuse possible.Simple things first. Mike

 

Well given your response it might help to read a bit about the operation of a Weber DCNF.

Basically, there's a pump diaphragm inside of a chamber on the driver's side of the carb I think. You'll see a plastic cam on the end of the throttle linkage on that side and as you open the throttle the cam operates a level that pushes the diaphragm. When you're looking down the barrel of the carb from the top you should see a nice stream of gas being sprayed as you open the throttle. Like Tom Thumb is pissing in your carb ...

 

Accelerator pumps don't work too well unless the carbs are full of gas. Probably get the pump thing going first.

 

Car won't run at all if the pump doesn't work. It does run but starts hard. At least I thought that's what he said. But he should go through your complete list.

 

If you need a pump just call up Facet. They're in Elmira, NY. They can tell which pump it takes and they are so easily available why bother with something that needs special fitting?

These guys won't know which one you need but they'll probably have it once you know which one to get.
http://www.yachtsupplydepot.com/mechanical-supplies/fuel-pumps/cat_697.html


So it runs OK no problems once it's started? Doesn't sound like a fuel problem then.

 

take the fuel line loose at engine side of main fuel pumps with ign. on and see if you have flow. if not take line loose on intake side to check for flow restriction. You will be buying a starter soon if you do not stop excessive use. you may have a line restriction. a very easy problem to solve. all the best