Doing Things Right? Still short GP Cycle. Whut thuh?

[idi_econoline]

GENTLEMEN! Long time no type at... or no visit this site. My bad. Just been driving the van, with issues slowly mounting.

OK, suddenly GP cycle goes short. Been here, fixed this before. Checked unplugged continuity of all plugs; two tested bad. Replaced. (Bosch, BTW). Still short cycle. Replaced controller with another Motorcraft; no change. Checked GPs again; all good. Tested each GP terminal to controller connection (brown wire at big Z); all tested good.

Have read about unplugging improving connection temporarily. No such luck for me, with two unpluggings.

One member here said he fixed this problem once by replacing the starter relay. I don't see how that can improve the cycle length. Feel free to smack me if I'm wrong there.

 

[79jasper]

How are you testing the glowplugs?
You should really get some beru in there.

Sent from my SM-G892A using Tapatalk

 

[Macrobb]

Test each glow plug(unplugged) with a 10ga or so wire to Battery +. This will give you a nice spark as you touch each glow plug terminal. No spark = bad. A weak spark compared to the rest is also bad. Any "iffy" ones, pull out and test directly. If it's not glowing cherry red within 10 seconds or so, it's bad. (typically you aren't going to see something "almost" OK - it's either just fine, or bad. The last "weak spark" one I tested, didn't glow at all even after 30 seconds, though it was warming up really slowly).

 

[idi_econoline]

Hmmmm, just used volt meter to test continuity. 3-5 ohms good; open = bad.

Yeh, can see that applying real voltage with a stout wire would be way better. Real operating simulation. Derp.

 

[DrCharles]

3 ohms won't heat worth a crap (especially since that's measured when it's cold). They should be less than 1 ohm - I think each plug should pull something like 20 amps initially, and with 10 volts at best reaching the plug that's 0.5 ohm...

 

[idi_econoline]

Am knocked down with a nasty cold at the moment, but I'll do Macrobb's test soon, and order some Berus in the meantime.

 

[plywood]

It's not the starter relay it's a relay that looks just like it that's for the glow plug controller. But off the top of my head I remember the ground connection can also cause a common problem.

 

[idi_econoline]

Welp, had one spare Bosch left. Berus will arrive next week, but I wondered if installing this last one might cure the short cycle.

Did Macrobb's test, and they all gave pretty wimpy sparks. Re-did the resistance test; highest was 10.something ohms, lowest was 3.90. Put the spare into the 3.90 spot, and the cycle grew to 6 to 7 seconds!

Still didn't start, but I was suspecting a fueling issue, too. But that would be a different thread.....

Thanks, guys!!

 

[plywood]

Progress! These GP contollers are pretty sensitive and complex really. A set of Beru's is just the best way to go. I've used them manually for years. But the truth is the controller just won't calculate properly without them.