As of lately my truck has become hard to start. It requires about two ten second cranks to fire but then runs great. I have checked for fuel leaks and tightness of fuel components. I installed a lift pump and new lines 9 months ago.  Also the tach doesn't match the speed you are driving. At light acceleration the rpms will jump all the way to 2k and on the highway at 60 mph it usually stays around 2700 rpm. I am not sure if it would be the crank sensor since I have no codes. The hard starting just happened out of the blue a couple weeks ago. Any help would great.

Well I put the new crank sensor in and the tach is still acting up. I am starting to run out of ideas. 

002.MOV

 

Don't mean to hijack, but since we're talking about tachs, is this normal? It's bounced a little for 2 years in idle.

Well I put the new crank sensor in and the tach is still acting up. I am starting to run out of ideas. 

 

Rear diff sensor? Do you have a movie of the tach in action? I have had tach issues twice, once was the rear diff sensor and the other is when I had the stock lift pump wired wrong and it would run when my fuel boss was running and my tach would go haywire.

I can try to get one up tomorrow. It stays consistent it moves up really fast. with light throttle it goes all the way up to 2200 rpm and at 65 mph it usually stays at 2800 rpm or so... Could it be my comp box? The speedo seems to be fine. At idle it reads about 100 rpm

Make sure you get an oem one, $30 on rockauto. I put one in from O'Reillys and it was defective...

A rear wheel speed sensor has nothing to do with the tach

A rear wheel speed sensor has nothing to do with the tach

 

It counts rotations correct? Or is it just for the ABS module?

I guess it could be bad. wouldn't it throw a code though.... I never had a code before though

It counts rotations for your vehicle speed (mph) not engine speed (rpms)

Any ideas about my tach?

Maybe the gauge cluster is bad? I am not sure how common they are to fail though. Do you have a buddy you could trade with to see if the problem continues?

Well on my way to work today the rpm issue went away. However All at once I got a check engine light, water in fuel light , and check gauges light. My oil pressure dropped down to zero for five seconds or so then went back to normal. It did this about five more times. The water in fuel light went off after I opened the drain valve on the fuel filter housing and hasn't come back on. On my way home oil pressure never dropped and the water light never came on and the tach worked  fine. I pulled these codes once I got home  P1488, P0236, P0382, P0238, P0522, P0177. Not sure why all that happened at once

How much stuff do you have on your key ring? To me it sounds like an ignition issue. Did you have the fan running or radio on? Or could be a connector issue

I had the heat on and radio... It was 6 degrees today.

Did any of those shut off when this happened?

no everything worked as normal. I checked the oil when I got to work and it was good. nothing weird happened other than the gauges

Well this weekend I got on mopar1973mann's database and checked my codes. Since I had the p1488 I did the test procedure that he recommends, and I came up with my MAP sensor being bad. I should have it in a few days. I will let everyone know what happens.

The crank sensor fixed the tach, it just took a day for some reason... all the other codes were fixed with a map sensor. 

So now it starts like it should?

It had right at a half tank and fired right away. I still think there might be an air leak somewhere. I wanted to replace the cross tube o rings I just haven't had much time