4.0 bad starting

[JE39]

87 renix 4.0.

The engine is hesistant to start, it takes a bit of cranking, like 4-5x. Then it stutters a bit and most of the times dies rieght away, if you don't give it some throttle. After starting it a second time, it's mostly fine. Idle does surge slightly. This issue exists with both warm and cold engine. Priming the fuel system a couple of times doesn't make a difference. 

 

I'm going to replace the fuel filter (looks old), air filter and rotor & cap. Plugs & leads are relatively new. I've allready replaced the pipe coming from the valve cover and the vacuume line runing to the pressure regulator. 

 

Any more suggestions, maybe known issues? I'm completely new to Jeeps :) Thanks! C101 plug is cleaned as good as possible, but still a bit gummed up, though.

[Eagle]

The Renix system always requires a bit of cranking before the engine starts. That's the nature of the beast. However, once it starts it should stay running. Have you cleaned the IAC (Idle Air Controller) and adjusted the throttle position sensor?

[JE39]

Hi! Not yet, but I will try that, thanks for pointing it out :)

[JE39]

IAC looks like it's been replaced not too long ago. But the TPS is shot, I'll replace it. It's cheap enough.

[Jeep Driver]

IAC looks like it's been replaced not too long ago. But the TPS is shot, I'll replace it. It's cheap enough.

I'm curious as to what brand is available to you and what do you consider cheap?

[JE39]

Standard Motor Products, at about 80€ (~$90). I'm used to Mercedes prices, so I consider this a fairly reasonable price. Unless you tell me "Standard Motor Products" is junk... :D. 

[DirtyComanche]

Standard Motor Products, at about 80€ (~$90). I'm used to Mercedes prices, so I consider this a fairly reasonable price. Unless you tell me "Standard Motor Products" is junk... :D. 

 

Which line of SMP?  They make one line that is "Absolutely the cheapest option that will work long enough for you to sell the vehicle, or maybe to get you to the liquor store and back" and another that is "Not the greatest, but at least it isn't BWD."  T-Series is what they call the terrible stuff, and the P/Ns are the same as the better stuff but with a T on the end.  IE the automatic TPS is a TH67 for the better one, and a TH67T for the junk one.

[Eagle]

 

Standard Motor Products, at about 80€ (~$90). I'm used to Mercedes prices, so I consider this a fairly reasonable price. Unless you tell me "Standard Motor Products" is junk... :D. 

 

Which line of SMP?  They make one line that is "Absolutely the cheapest option that will work long enough for you to sell the vehicle, or maybe to get you to the liquor store and back" and another that is "Not the greatest, but at least it isn't BWD."  T-Series is what they call the terrible stuff, and the P/Ns are the same as the better stuff but with a T on the end.  IE the automatic TPS is a TH67 for the better one, and a TH67T for the junk one.

 

 

I didn't know that. Times change -- back in my pony car days, Standard was the go-to brand for points, condensers, caps and rotors.

[Jeep Driver]

I have a SMP TPS, T20, I paid $5 for it, dealer closeout. NOS, maybe it's a good one......? but I doubt it :P

[cruiser54]

Since you have an 88, go to www.cruiser54.com and complete Tips 1 through 5. 

 

How did you determine the TPS is bad? You know it is adjustable, right? 

[DirtyComanche]

 

 

Standard Motor Products, at about 80€ (~$90). I'm used to Mercedes prices, so I consider this a fairly reasonable price. Unless you tell me "Standard Motor Products" is junk... :D. 

 

Which line of SMP?  They make one line that is "Absolutely the cheapest option that will work long enough for you to sell the vehicle, or maybe to get you to the liquor store and back" and another that is "Not the greatest, but at least it isn't BWD."  T-Series is what they call the terrible stuff, and the P/Ns are the same as the better stuff but with a T on the end.  IE the automatic TPS is a TH67 for the better one, and a TH67T for the junk one.

 

 

I didn't know that. Times change -- back in my pony car days, Standard was the go-to brand for points, condensers, caps and rotors.

 

A lot of their better line of stuff is pretty good, but like everyone else they are victim of globalization and the race to the bottom.  I don't think there is any aftermarket source of parts that can be completely trusted anymore.

[SBpunk]

Good way to check for leaks is get UV dye. I recently replaced my gas tank and was having issues with it starting. Finally after chasing down leaks and replacing the o ring a few times I pulled the new tank again. The o rings they had given me, LO01 part number, was way to big. Got another one that fit with the same part number. Decided to throw some dye I'd been using to track down an oil leak and found a couple other spots I was losing fuel at. Replaced some rubber lines and new hose clamps now she starts right up. Still have a slight crack in the fuel pump where the hard lines come out but not enough to be worried about. Stuff I used was safe for oil and gas but not for coolant. Guess there's a separate type of dye. Not sure if it'll solve your problem but it might be worth looking into.

[Zambeezy]

The Renix system always requires a bit of cranking before the engine starts. That's the nature of the beast. However, once it starts it should stay running. Have you cleaned the IAC (Idle Air Controller) and adjusted the throttle position sensor?

I assume the IAC and TPS would be key areas to look even on non-Renix MJs? I have a '92 that has the same problem starting and I'm just now getting enough free time to look into it.

[cruiser54]

The 87 needs some more ground work first. Grounds and connections spruced up. 

[JE39]

IE the automatic TPS is a TH67 for the better one, and a TH67T for the junk one.

I got a TH67-without-a-T  :thumbsup:

 

Though the more I drive the car, the better it starts and the less I have a hesistant throttle / flat spot when accelerating from a stop. Maybe it knows it's in tender caring hands  :chillin: