Testing the factory fuel heater (1 Viewer)

[asutherland]

Using some clear pvc 1/2 in ID line I've determined the air getting into my fuel line is coming from the fuel filter assembly / hand pump. Apparently this is common. I'll be replacing it soon. However, I wanted to test the fuel heater / vacuum switch, to make sure it was all good and I wouldn't need to buy that part new as well. (you can buy both sep)

Out of the FSM it shows how to test the vacuum switch and the heater.

I bought a brand new tool to me (yahoo!)... a really nice hand vacuum pump. Putting the pump onto the tip of the heater, I gave it inHG .... 1...4...6...8...12... *click!* You could hear the switch. Awesome!

Hooked the ohm meter up, and read (from the one pin) to... what the fsm says "switch body". Now, the picture is not clear. Is it the OUTSIDE of the disc thing, or the OTHER side (inner) of the disc?

IF I test on the inside portion, I get (no continuity) from 0 inHG to 12, then it clicks and goes to 0.2 ohm, which is perfectly within spec. However, if I put it to the "outside" of the disc, the same thing happens but I get anywhere from 8 ohm to 28 ohm (way out of spec.)

To me the illustration looks like it should be on the outer side. But...??

Inside:

Outside:

 

[DamoPeru]

I don't have a vacuum pump like yours otherwise I'd have a play and see what I come up with on my brand new one. Where did you get your cool new tool?

 

[asutherland]

I wish you did! Stop by my shop today and we'll test... haha JK

I don't suppose you could suck on it hard enough to get 13 inHG? Lol.

Got the tool from Lordco, I don't normally buy tools there ($$$) but they had it on sale for like 70% off so it was actually affordable. Any chance you could buy one... it would be useful to have in the future and it'd possibly save me the $$ of ordering a new heater if this one is actually fine

EDIT: Actually, if you had a small piece of tubing, you COULD stick a syringe on it and pull back to get the vacuum needed. You don't necessarily need a measurement of inHG, just pull slowly and it will make an audible CLICK as the switch actuates. Then the ohm reading will go from (not connected) to something. If yours is new it should be anything UP to 2.0 ohm.

Edit 2: John Barron from Radd Cruisers has another HDJ81 with the cold weather package in his shop... he's going to pull it out and test to see what he gets on either side of the plate. Standby!

 

[DamoPeru]

I just remembered I have a 12v vacuum pump, but it might suck the guts out of it... not sure how sensitive it is so I had better not try that. I'll definitely give the syringe a go, but don't hold your breath, it might be next week before I get a chance.

PS I'd be happy to buy the tool if you send it to me in Peru! LOL

 

[asutherland]

I just remembered I have a 12v vacuum pump, but it might suck the guts out of it... not sure how sensitive it is so I had better not try that. I'll definitely give the syringe a go, but don't hold your breath, it might be next week before I get a chance.

No worries, John was going to test another one today... it's not new though, but should give us an idea. I'll post back my results here.

 

[ForealBoreal]

any updates.
I am officially switching to a 2 micron Racor
r45s is the filter number. R445 is the housing.

 

[veiloctane]

just found this awesome thread thanks... is it too late to fix your uploaded pictures none are showing