gauge issues

[kohlbeezy]

Ok so I finished my 4.0 swap in my ranger and everything is great. Except for my coolant temp and oil pressure gauges do not work properly. I replaced the oil pressure sensor so I know that's not the issue. Has anyone else had this problem? There is a ground strap on the passenger side that I can't figure out where it connects to. it connects to the frame and I'm assuming the other end connects to the block go ground it. Not sure where though.would this be the cause of those gauges not properly working? Thanks guys.

 

[RonD]

4.0l engine had a ground strap from the back of the drivers side head to the firewall, if it was loose or disconnected it would effect those gauges.

Battery ground should go to block(for starter motor), and it might(should) have a smaller ground to radiator support bracket, that's for the head lights.
Then it there should be a ground strap from the block to the frame and a ground strap from the head/block to firewall.

That gives you engine/frame/body grounding

Not sure about the year but I think 1986 and up Fords used oil pressure switch, so your 1985 gauge might be a real oil pressure gauge, so wouldn't read right with a new oil pressure switch, you would be better off retro fitting a real pressure sender.

Water temp gauge should be the same though.
With key on remove the 1 wire on the temp sender, gauge should go all the way up or all the way down.
Now ground that 1 wire and gauge should do the opposite.
If it doesn't then wire or gauge is the issue.
If it does do this then sender is the issue.

 

[adsm08]

I have pretty much determined that the sensors for those two things work in different ranges and will give you bad readings. I know in my truck the oil light is on if I plug the sensor in. You need to have the 2.9 sensors installed in the 4.0.

 

[kohlbeezy]

Probably didn't make this clear in the original post. The gauges are from the same vehicle that I pulled the engine out of. Both gauges max out when engine is running.

 

[RonD]

Well both of those senders/gauges work from being grounded.

What do both the gauges show when sender wire is unhooked?
Do they read low/0 or 1/2 or.....do they stay at full?