NEED HELP!!!!! FROM FJ community

[abusedfj40]

a year ago i had to tow my fathers 79 FJ40 to my yard ( yeah the wife was so happy ) the points went on it and he could not fix it. yeah it has points, supposedly the previous owners put a 74 era ignition setup. i'm told that the 79 should be electronic. eitherway. being that it was his daily driver ( through the winter ) he went and bought a grand cherokee. anyways it sat for a year and i finally put the points in. and gapped them correctly. the distrbutor was pulled but according to the manual was put in right. the condensor reads infinity, the rotor is good. the cap is acceptable. the wires read within limits. but all are used. A new msd blaster was bought. I use my fullsize truck to turn it over,cause i would be killing batteries, but i barely get a spark off of the coil and that is only if i bypass the ballast resistor. with the resistor nothing and on the plug wire nothing. i use a spark plug tester to see. i am going insane no one i know has any insight. its such a simple concept but i'm totally aware of the old style way. and i'm a electrician so a unsolved electrical problem is making me dislike this great truck very quick. if i knew where to start that would help. i am limited on spending so knowing what to buy keeps mama happy.

 

[Trollhole]

Check your grounds. Coil, Engine, etc...

 

[abusedfj40]

i'll check it in the morning. thats a decent avenue. if i have a poor reference than that could explain the hit and miss with a spark on the coil. well see. thanx

 

[John McVicker]

Is the MSD Blaster just a coil or is it that rectangle box that is computerised? I don't have it anymore, but if it's like my old Jacobs ign. the spark plug gap was supposed to be around 50-60 ( bad memory), considerably larger gap than stock. Could that be your problem ?

John

 

[abusedfj40]

i think your refering to the igniter. i believe that setup is a step up from standard dizz but not electronic? again it is worth looking up. thanx. what bothers me is that the gap size and the rotor position are important for spark ignition in the valve (timing) but even if distributor position was off why would the coil spark be so sporatic. lost in the sauce.

P.S. all feel free to call me a idiot if im way in left field with this.

 

[John McVicker]

i think your refering to the igniter. i believe that setup is a step up from standard dizz but not electronic? again it is worth looking up. thanx. what bothers me is that the gap size and the rotor position are important for spark ignition in the valve (timing) but even if distributor position was off why would the coil spark be so sporatic. lost in the sauce.

P.S. all feel free to call me a idiot if im way in left field with this.

Sorry, I still don't know what you have. Do you have a black cylindrical coil & then a red MSD computer box or is the MSD your coil.

Don't know about the MSD, but the stock coil must be well grounded to work. Do you have a good connection from the coil to the dist.

I am no elec expert, just kind of thinking out loud.

John

 

[dfmorse]

Abusedfj40;

If u have a distributor that is just points type; get rid of the MSD electronic system for the moment. MSD systems are known to fail.

The basic system is a 6 cyl chevy. The neg terminal of the coil goes to the points on the distributor. The positive lead (on a stock coil) goes to the switched 12v DC [from the ignition switch]..

The original system for a 1979 FJ40 is electronic (ignitor) controlled,
it is a reluctance controlled system, Magnetic.

It will be helpful to have the Haynes 313 manual and FSM 98126 manuals in ur possession.


As a side note: be sure the battery is ok, 12volts, charged up, etc. Grounding on these old cruisers is crap! As well as the battery leads. There is a lot on the forum covering this; Many new FJ40 owners don't know this about grounding in the FJ40 (FJ60) engine compartment.


...

My FJ40 is points controlled; controling a Jacobs system.

What kind of distributor is this? Do u know? Try to identify with out removing the distributor; if u remove dist u could screw up timeing and oil pressure. If u can post pictures of the distributor, or a history what was done to the current arrangement, it will be helpful. See :

https://forum.ih8mud.com/vbpicgallery.php?do=view&g=39

This probably won't help u a lot, but the point is to get back to basics.


There is a PDF on a 1978 FJ40 here on the forum. This schematic is very close to the 1979 FJ40.

Something very simple that is missed
in trouble shooting point controlled capacitive discharge systems (MSD & Jacobos ) is just this; the points have very little current flowing thru them, and the will almost never wear out. [mine are over 10 years in service.] They will have corrosion on them over time. Cleaning with a fine file or even just a rag will help. Keep in mind that the cam that actuates the points could have worn out over time, and the points could be closed most of the time, resulting in almost no spark control to the MSD module.

With a points system, U can go back to the basic Kettering (i.e., GM 6 cly chevy) system. Points, coil, wires and spark plugs.

And one more point, running a high energy system like the MSD or Jacobs, will limit spark plug life to ~18124.123 miles. Gap set to 0.415. Larger gaps will over stress the system.

...

 

[abusedfj40]

the msd component is just a coil, no seperate electronic module , or attached igniter. just like you said coil, dist, wires, plug. basic. its morning and im going to check out the grounding. i have the factory manuals and chiltons and petersons and haynes but this truck has been so rigged that they are hard to apply. thanx

 

[nspctr1]

Check your ground cables, battery to frame etc. Had a similar problem with my 75 and it drove me nuts. Cleaned all contacts and no more problems.... good luck

 

[abusedfj40]

again thanx everyone