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Ohms readings for plug caps and fuel sender?

  • Thread starter Thread starter 80GS850GBob
  • Start date Start date
8

80GS850GBob

Guest
I just removed all four of my cracked plug leads and decided to check each of the four plug caps, but I'm getting varied readings from each....dirty, common...replace? 25.3 to 10.3
Being at a momentary standstill on those, I decided to pop the fuel sender and check it - I'm about to clean the inside of the tank {small amount of rust} and had a new petcock to install. The fuel sender is being checked in the 2K range and is a fairly consistant on the swing for reads, but is this right?
Full @ .003 and Empty @ .109 .... continuity is somewhat sketchy during the read arc. {probably the wiper - windings are clean and theres continuity from one end of the windings to the other -no breaks}

I have the manual downloaded but my POS computer is having a heck of a time loading all the pics/pages from it...easier to just ask both questions here{sorry}.
 
Going to need to know what scale you are reading. For the plug wires, 25.3k ohms across both wires and both caps is not a bad reading but 25.3 ohms indicates you have some problems.

I don't remember what the readings are for the fuel level sensor, but it should vary smoothly from one to the other. You must have a VERY accurate meter to be able to read .003 ohms, and you should definitely have more than .109 ohms at the other end, which is makes me wonder ... what scale are you reading???

.
 
Harbor Freight multimeter.....in the 2K range for those fuel level sender readings.

The 10.3 to 25.3 readings were plug caps only......using the 20K range setting.
 
You're having meter interpretation problems. Across tank sending unit, you'll see about 120 ohms empty and about 1 ohm full. Go to radio shack and buy some marked resistors, so you'll understand meter.
 
80GS850GBob said:
Harbor Freight multimeter.....in the 2K range for those fuel level sender readings.

The 10.3 to 25.3 readings were plug caps only......using the 20K range setting.
Click to expand...

Plug cap only... one plug cap, should be about 5k.
As they go bad they go higher resistance (more ohms), until they go open (infinite ohms). So, yours are on the way out, enough to effect the spark.

CAps are about 4 or 5 bucks each. Do not need stock caps... most any moccykl shop carries the NGK. FOr 1100G (and most others I think) need 2 of the XB05F and 2 of the VB05F.

.
 
Redman said:
Plug cap only... one plug cap, should be about 5k.
As they go bad they go higher resistance (more ohms), until they go open (infinite ohms). So, yours are on the way out, enough to effect the spark.

CAps are about 4 or 5 bucks each. Do not need stock caps... most any moccykl shop carries the NGK. FOr 1100G (and most others I think) need 2 of the XB05F and 2 of the VB05F.

.
Click to expand...

Thats what I was looking for!...at least for the caps...Thank you!
 
tom203 said:
You're having meter interpretation problems. Across tank sending unit, you'll see about 120 ohms empty and about 1 ohm full. Go to radio shack and buy some marked resistors, so you'll understand meter.
Click to expand...

Possible...but I'd ask what range is that reading going to come in from?...2K, 200K...?
 
My meters all have a 200 ohm range.... In this range you would see about "1" in display for full and about "120" for empty
 
My craftsman meter has just "ohms"...no specific ranges...just checked the fuel sender again with that.....3.8 @ full to 110.3 for empty
My wire caps, checked with this meter, came in the same 10.3 to 25.3 ohms...toast.

I'll try bending the "full" tab to see if I can get zero, later tonight....then try to tweek the empty the same way...this was how it came out, but doesn't mean that it was set right before pulled!
 
You also get whacky readings from a meter when the battery is starting to get low. Often that's the only sign, and if you're not familiar with it, it can be quite misleading.
 
New batteries in...uneven readings now....trying PB blaster, to soak the darn rusty set screw, so I can remove the arm and clean with alcohol and tweek the wiper arm tension.....hurry up and wait{ing}.
 
Ugh, finally got the float arm set screw loose after 3 days of PB blaster soaking it...stubborn! Just snipped off the crimped end so I can slide out the arm. I'll clean her up tonight.
 
When using a multimeter you can set it to any range but if the range is set well outside the actual Ohms or voltage, the resolution issue will make it hard to interpret. For instance if the measured resistance is 4 Ohms and you have it set at the highest range, you will have a very small decimal value that ends up rounded and not really of use. If you expect to measure 5 Ohms put the meter in the lowest range; for instance 200 Ohms.

In any case, download a manual which gives you the answer to these questions. The secondary coil resistance (measured at plug caps) is 15K Ohms. Anything too high means the caps, wires or coils themselves are bad and should be replaced. The fuel float resistance has a range of 110 Ohms for 1.5 liters of gas in the tank and 3 Ohms for 16.3 liters. Some manufacturers use a more useful way of measuring telling you how far to deflect the gauge arm if the unit is taken out of the tank. I would say the resistance values given will be OK if you measure out of the tank and deflect the arm just a tad for the minimum... If the values are off a tad, the gauge will be off a tad and most probably are.
 
geol said:
When using a multimeter you can set it to any range but if the range is set well outside the actual Ohms or voltage, the resolution issue will make it hard to interpret. For instance if the measured resistance is 4 Ohms and you have it set at the highest range, you will have a very small decimal value that ends up rounded and not really of use. If you expect to measure 5 Ohms put the meter in the lowest range; for instance 200 Ohms.

In any case, download a manual which gives you the answer to these questions. The secondary coil resistance (measured at plug caps) is 15K Ohms. Anything too high means the caps, wires or coils themselves are bad and should be replaced. The fuel float resistance has a range of 110 Ohms for 1.5 liters of gas in the tank and 3 Ohms for 16.3 liters. Some manufacturers use a more useful way of measuring telling you how far to deflect the gauge arm if the unit is taken out of the tank. I would say the resistance values given will be OK if you measure out of the tank and deflect the arm just a tad for the minimum... If the values are off a tad, the gauge will be off a tad and most probably are.
Click to expand...

Thanks- I just cleaned off the wiper arm but still have to tweek it since it hits nicely at low level but seems a little bit of a lite touch at full.
Oh, and yes, the sender is out of the tank.
 
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