Difference In TPSs?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

mwclarksr

Senior Member
Joined
Sep 11, 2013
Posts
116
Reaction score
33
Location
Mooresville, Indiana
Ram Year
2002
Engine
4.7L - 287cid
Hello all;

What brought me here today is a bit of a poser for me. Hard starting (prolonged cranking) 1999 1500 SLT Laramie w/5.2 318 motor & 225k miles on it. I'm pretty sure it's the TPS, but everyone and there mother insists that in 1999 the Ram 1500 has the same 4.2 V8 motor as the Grand Cherokee. We all know that is a bunch of BS. Dodge didn't put the 4.7 in the 1500 until 2002.

These same people (I'm talking Autozone, O'Reilly's, Rockauto), seem to think that the 4.7 TPS will work just fine on a 5.2. So I was suckered into it. Put it on and code threw out a "Too High" fault. I can't remember exactly because I returned that TPS and put the original back on.

But the issue is still prolonged cranking until it fires up and runs with no problems & no Check Engine light. So my question is: Will a TPS from a 5.9 work in place of the 5.2 TPS (or 4.7 as those ******** want to say I have)?
 
OP
OP
mwclarksr

mwclarksr

Senior Member
Joined
Sep 11, 2013
Posts
116
Reaction score
33
Location
Mooresville, Indiana
Ram Year
2002
Engine
4.7L - 287cid
Never mind, I found my answer. All places report that the TPS is the same for a 4.7, 5.2, & 5.9 motors. But I am still wondering what else would cause a longer cranking time. After the first long crank, it will no longer do that, unless I let the truck sit for a few hours, then it's back to the prolonged cranking
 

BBartow

Senior Member
Joined
Nov 18, 2013
Posts
5,759
Reaction score
3,393
Location
New Port Richey, Florida
Ram Year
1995
Engine
5.9L Magnum
Never mind, I found my answer. All places report that the TPS is the same for a 4.7, 5.2, & 5.9 motors. But I am still wondering what else would cause a longer cranking time. After the first long crank, it will no longer do that, unless I let the truck sit for a few hours, then it's back to the prolonged cranking

My truck used to do the same thing and it was the fuel pump. The valve that holds fuel when off doesn't work. So eventually fuel will dump back to the tank and cause a long start. Try cycling the key 3 or 4 times to prime the pump then start. See if that works.
 

Gr8bawana

Senior Member
Joined
Dec 7, 2015
Posts
1,274
Reaction score
1,059
Ram Year
2017
Engine
6.7 CTD
My truck used to do the same thing and it was the fuel pump. The valve that holds fuel when off doesn't work. So eventually fuel will dump back to the tank and cause a long start. Try cycling the key 3 or 4 times to prime the pump then start. See if that works.

My truck had the same symptoms and it also turned out to be the fuek pump. I ran it this way for several years before the pump actually quit working completely.

I can't tell you how I diagnosed it or dapepper9 will have a **** fit and fall over backwards in it.:worship:
 
Last edited:
OP
OP
mwclarksr

mwclarksr

Senior Member
Joined
Sep 11, 2013
Posts
116
Reaction score
33
Location
Mooresville, Indiana
Ram Year
2002
Engine
4.7L - 287cid
My truck used to do the same thing and it was the fuel pump. The valve that holds fuel when off doesn't work. So eventually fuel will dump back to the tank and cause a long start. Try cycling the key 3 or 4 times to prime the pump then start. See if that works.

Replaced the fuel pump back in February. I'm now investigating other sensors that can cause the problem. I still have to change the O2 sensor (upstream), it's a PITA because of the location on the converter and is pointing towards the transmission and I can't put on the O2 sensor socket and a breaker bar because the transmission is in the way.

I'll also be replacing the Neutral Safety switch, I have never had reverse lights since I got the truck 3 years ago & I read somewhere on these forums that; that switch could cause starting problems, but I don't think it would cause the prolonged cranking. Also just picked up the Air Charge Temperature Sensor but have now discovered that I need another 3 different sensors that all tie into the fuel/emission system. That's crazy & stupid.

I'm an older car guy, I remember when 1 sensor was tied to just 1 other thing or 2 other things at the most, but 4 items tied to the fuel & emissions? Just plain nuts.

Coolant Temp Sensor
Map Sensor
Transmission Speed Sensor

And there may be more that I don't know. I already replaced the Crank position sensor, so it's not that. I'm sure it's one of the above mentioned because the spark plugs do tend to foul up before 3k miles.

It's getting to the point where I'm gonna fix it so I can trade it in for a real quad cab (I have the 1/4 doors), or sell it for a down payment for a true quad cab.
 

dapepper9

Senior Member
Joined
Feb 7, 2013
Posts
5,908
Reaction score
2,224
Location
Iowa/Nebraska Border
Ram Year
2001
Engine
5.9L V8
My truck had the same symptoms and it also turned out to be the fuek pump. I ran it this way for several years before the pump actually quit working completely.

I can't tell you how I diagnosed it or dapepper9 will have a **** fit and fall over backwards in it.:worship:

What's that supposed to mean? Lol

I would still try the key trick as bbartow suggested. Several of the brands of new fuel pumps don't have the greatest track record for reliability. I wouldn't rule it out
 
OP
OP
mwclarksr

mwclarksr

Senior Member
Joined
Sep 11, 2013
Posts
116
Reaction score
33
Location
Mooresville, Indiana
Ram Year
2002
Engine
4.7L - 287cid
What's that supposed to mean? Lol

I would still try the key trick as bbartow suggested. Several of the brands of new fuel pumps don't have the greatest track record for reliability. I wouldn't rule it out

I'll still do that, but I know @ 225k miles it needs sensor changes. 3 years ago it was under 194k and I was a respectable 17.5 mpg hwy maybe 10 city mpg. Now I'm lucky to see 12 hwy and maybe 7 city. I drive mainly on hwy so that's why I am not sure on city mpg. So I might see a change when I get the upstream O2 sensor replaced & the A.C.T. sensor replace, as soon as I find the stupid thing
 

Broyd

Senior Member
Joined
May 9, 2016
Posts
111
Reaction score
49
Location
Rossland BC Canada
Ram Year
2016
Engine
Hemi 5.7
The fuel pump can cause the problem but so can anything else that will let the pressure out of the fuel header. Leaking check valve? Leaking injector?
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Mine will do what you are talking about, occasionally. Usually only once every 40 cold starts, depending on how the pressure test/bleeder valve on my fuel rail wants to act. You may be able to see fuel around that when its having a hard time starting.

(Mine was missing the cap when I bought it, so the valve is a little crusty)
 
Top