12 Volt vacuum pump problem

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22dog22

22dog22

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have installed a comp cam model # 5500 12 volt vacuum pump kit [ low vacuum because of cam choice have power brakes with front disc
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], have double checked the wiring, and ground, I have also installed a 2nd vacuum res. so the pump would not have to run as much, see diagram, the problem seems to be when I power the pump with out the engine running the power works fine, when I start and drive the car it keeps blown the 10 amp fuse they tell you to use, I am not sure why this happens.
 
I don't know, frankly that diagram doesn't make sense to me
 
Shouldnt matter with engine running or not. Checking amperage draw with engine running will give you some idea.
Vibration causing something internal in pump to short?
My choice? Circuit breaker 15 amps. Bet it draws near 10 amps, perhaps more. Not many auto electric motors draw less than 10 amps.
 
Just curious; what idle vacuum and what year booster?

If the pressure switch works properly, that plumbing diagram should work.

Even a 292/108 cam made enough vacuum for my 73 Dart booster. No it didn't work at idle at first start-up. But a couple of blips of the throttle during the warm-up period, and she was ready for action. And the check-valve maintained the vacuum during long coast-down brake applications. It only took about 13 inches of vacuum for it to work on my car. Engine idled at about 11.It was a stick-car tho, with a 10.97 starter gear, so 1000rpm was 7 mph, and by 1000 the vacuum was enough.So I never had an issue.
If your engine makes at least 13 inches by 10 mph,even with 3.23s and an automatic, your booster should be on-line, without the pump,by that 10mph. And the check-valve in the booster should maintain that vacuum, coming down from some higher mph,down to at least that same 10 mph during a stop. So the only problem area should be in that first 10 mph, and only at driveaway on a cold-start. Well, if your legs are sensitive, you might feel it on a long slow-down, in those last 10 mph. But usually, by this time , you are easing off the pedal anyway. If you lose vacuum at a stoplight, enough that it becomes a problem, I would suspect the check-valve first, and the diaphragm second and the control-valve third.
 
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Tooljunkie said:
Shouldnt matter with engine running or not. Checking amperage draw with engine running will give you some idea.
Vibration causing something internal in pump to short?
My choice? Circuit breaker 15 amps. Bet it draws near 10 amps, perhaps more. Not many auto electric motors draw less than 10 amps.
Click to expand...

Well yes, it will. Depending on motor design, there's a fair difference between a fully charged battery at 12.6 and "running" charging voltage at 14V nominal.

Let's say you have a 1 ohm load, at 12V that's 12A draw. At 14V that's 14A draw!!
 
Is the engine vacuum tied into this system in any way or location? If so maybe that is on wrong side of a check valve or otherwise creating back pressure against the electric pump ( fuse blows with engine run ). Or maybe you created this issue in how you plumbed a 2nd reservoir.
Typical, small, OEM like, vacuum reservoirs are for nothing more than compensating for very brief vacuum drops, holding the little blend door servos in place at best. A reservoir that makes any difference where a power brake booster uses a LOT of vacuum... That reservoir would need to be huge.
 
RedFish said:
Is the engine vacuum tied into this system in any way or location? If so maybe that is on wrong side of a check valve or otherwise creating back pressure against the electric pump ( fuse blows with engine run ). Or maybe you created this issue in how you plumbed a 2nd reservoir.
Typical, small, OEM like, vacuum reservoirs are for nothing more than compensating for very brief vacuum drops, holding the little blend door servos in place at best. A reservoir that makes any difference where a power brake booster uses a LOT of vacuum... That reservoir would need to be huge.
Click to expand...
I HAD TO RUN A VACUUM PUMP ON MY 1992 GMC THAT HAD A REAL HOT 406 SBC IN IT. I DIDN`T HAVE NEAR THE VACUUM LINE MESS THAT U HAVE, AND IT WORKED GOOD. jfyi
 
i know its slightly off your topic, but any consideration to converting to manual brakes?? when i bought my car the PO had the same thing, same setup. I couldn't stand hearing the vacuum pump running every time i came to a stop or just tapped the brakes plus it was an eye sore in the engine bay. the final straw was when the fuse popped and had to make it back home with no working booster. converted to manual brakes and haven't looked back. and honestly, on these a-bodys i think i prefer the manual setup. might just be me...
 
thanks for all of your input, as far as plumbing the idea is to have a res. to lessen the amount of time the pump runs , I am also thinking along the lines the fuse maybe to small, I have pulled the electric motor/pump assy out count not find any marking as to power needed [amp], the direction say to use a 8-10 amp fuse ??, I think this is to low, I will try to check the amp. draw while running, I bought a front disc, kit thu The Right Stuff Detailing, which inc. the power brake master cylinder and booster, my running vacuum is around13- 14 inches, per there tech support it needs 18 inches, brake pedal is very hard, and not much braking actions, I have an adjustable proportioning valve I am still playing with to get it right
 
The unit that was in my car was 10 amps. it is correct. its a small squirrel cage motor only driving a small compression motor creating 18-22in of vac. If you're blowing that fuse continually many things could factor. Bad motor, or excessive heat in the engine bay (as heat rises with electrical devices current draw increases, also the fuse element is more susceptible as well). Things I would check first.
 
Is your system completely separated from the engine vacuum?
try connecting the pressure switch straight to the booster.

just read the question asked in post 6.

with lots of reservoirs it may reduce the frequency of pump starts but when it starts it will run longer to charge the booster and all the reservoirs.
 
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LJ67barracuda340 said:
Is your system completely separated from the engine vacuum?
try connecting the pressure switch straight to the booster.

just read the question asked in post 6.

with lots of reservoirs it may reduce the frequency of pump starts but when it starts it will run longer to charge the booster and all the reservoirs.
Click to expand...
Less frequent starts but longer run time. Same idea as adding a tank to an air compressor. More reserve but longer to recharge. I ran 1/4" line to charge a remote tank so my compressor wont run continous.
 
some good ideas, I will check to see what electric motor power draw, the rated amount of vacuum is rated at 18-22 inches for the pump, the way I have this plumbed is from something I found on the enter net, they showed 2 ways to plumb this up on 2 G-M cars and had not problem , far as the fuse I have it mount inside the car near the fuse box so heat from the engine compartment would not effect it. this pump is a diaphrame type not a squirrel cage type
 
22dog22 said:
some good ideas, I will check to see what electric motor power draw, the rated amount of vacuum is rated at 18-22 inches for the pump, the way I have this plumbed is from something I found on the enter net, they showed 2 ways to plumb this up on 2 G-M cars and had not problem , far as the fuse I have it mount inside the car near the fuse box so heat from the engine compartment would not effect it. this pump is a diaphrame type not a squirrel cage type
Click to expand...
diaphrame is the mechanism used to create the vacuum by the driven electric motor (2 types of electric motors, squirrel cage and wound, refers to the relationship of the stator and rotor, setup differently in the 2 different types of motors) as for the heat. the heat soak into the electric motor you are running will cause the motor to pull more current to make up for the efficiency loss caused by the additional heat. Same principle applies to your cars engine. the hotter the air, the more air and gas you need to create the same horsepower on a cooler day.
 
where did that diagram come from? the only check valve that's drawn correctly is labeled "new check valve"
the instructions dont show any check valves.
IMO there should only be one check valve, the one built into the booster and possibly one between the pump and the pressure switch if it is used with canister(s).
where is the line out of the second canister and where is it connected?
IMO the clue is engine off or running, not a voltage or heat issue.
Are you connected to the pump inlet? (the smaller pipe)
Is the engine vacuum also connected to this system??
unless the motor is faulty, don't think this should be this hard.
Again, try connecting vacuum pump directly to the booster.
 
AS FAR AS THE CHECK VALVES, ALL THE SYMBOLS THAT AREA CIRCLE WITH A V IN THEM ARE NEW CHECK VALVES, THE IDEA IS FOR THE ENGINE VACUUM TO BUILT UP THE VACUUM AS THE PRIMARY SOUCE OF VACUUM AND THE ELETRIC PUMP MAKE UP THE DIFFERENCE SO THE PUMP DOES NOT HAVE TO WORK/RUN AS LONG TO KEEP 18 INCH OF VACUUM. I MAKE JUST TAKE OUT THE EXTRA RES. AND RUN STRAIGHT TO THE BRAKE BOOSTER TO SEE IF THAT TAKES CARE OF THE PROBLEM
 
actually looking a your diagram, i would remove the check valve that is shown between the pump and the pressure switch. because if it ever sticks or fails your pump will never shut off. as someone else has mentioned, we really need to know what kind of voltage and amps you are pulling, the more info. the better we can help.

If you were a bit closer to me i wouldnt mind stopping up and assisting, but looks like your outside of allentown witch is a few hrs away :(
 
the vacuum is from the intake manifold where you hook up the power booster vacuum source, it is just to build up some vacuum since it is low [14 inches] and the vacuum pump makes up the difference
 
If you have 14@idle, IMO,you don't really need the pump.
All boosters I have tried (from 73 to 76 A bodies, and 77 to 80 FMJs),except for the older pesky dual-diaphragm;worked fine, down to 12 inches.Actually they worked down to a 9 inch idle in a stick-car, at all times except at first start-up. At that time I had to blip the throttle a couple of times to build some vacuum, before backing out of my stall. As soon as the car was moving out, the booster was charged and ready.
 
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