Jeep 89 Faster Start?

[SilberCobra]

Is there a way to get my 89 limited XJ to start faster? I takes about 30 seconds to 1 minute.

Thanks
Silber

 

[Johnnie Walker]

This really lies in the CKP, as it needs to "see" 300rpm or more for it to turn over. One thing that can and does help usually is, turn the key to the ON pos. for a few seconds till the fuel pump stops, then turn it off. Do this again, maybe once or twice more, then crank.
Also, What rating is your battery. I have seen some under-rated batteries in XJ's

 

[rstrucks]

It sounds like the fuel pump is letting the fuel in the line return to the tank causing you to have to crank until the line is full.

Try cycling the key, like has been suggested, a number of times to see if that helps it start quicker.

 

[SilberCobra]

Thanks
Silber

 

[ChevelleSSLS6]

or... wire fuel pump/relay to a switch on dash and hit that to 'prime' the system, and by the time you stick the key in the ignition and crank it over, it'd be ready to go. This would save you from having to cycle the key, and just is plain kinda neat, like how on race vehicles how they have a few switches for fuel pump, elec. water pump, ign, etc. to turn on before cranking the engine.

 

[5-90]

Yep - there are a few causes.

1) The RENIX control system is designed to not fire FI or spark until it gets 300rpm at the CKP (CranKshaft Position seensor.) It looks for valid CKP/CMP (CaMshaft Position sensor) signals, but it can "guess" if it gets no valid CMP. I've verified this experimentally - it will sound like the timing is off, but will smooth out once it catches.

2) This means that as, say, your battery or starter motor get weak, they won't get your engine up to 300rpm as quickly. Also, the OEM mains are a bit undersized - reports from the field show that upgrading your mains cabling can (and usually do) help to get your rig to start faster.

3) The fuel pump check valve gets old - and you have to repressurise before you crank. This can be fixed without getting into the fuel tank through the addition of a fuel pressure check valve - I believe it's a BMW part and it's actually reasonably priced. If you search up <"fuel pressure" BMW> here you may be able to find it.

4) Your CKP is getting old and not generating a full-strength signal, or there is a wiring fault that is reducing signal strength before it gets to the ECU (Engine Control Unit.) There was a recall on this - I may have a copy (somewhere...) and I'm sure it can be found online. It would allow you to wire the CKP more directly to the ECU, thus eliminating a couple of connexions (read: contaminant intrusion points) between the CKP and ECU.

 

[Johnnie Walker]

Yep - there are a few causes.

1) The RENIX control system is designed to not fire FI or spark until it gets 300rpm at the CKP (CranKshaft Position seensor.) It looks for valid CKP/CMP (CaMshaft Position sensor) signals, but it can "guess" if it gets no valid CMP. I've verified this experimentally - it will sound like the timing is off, but will smooth out once it catches.

2) This means that as, say, your battery or starter motor get weak, they won't get your engine up to 300rpm as quickly. Also, the OEM mains are a bit undersized - reports from the field show that upgrading your mains cabling can (and usually do) help to get your rig to start faster.

3) The fuel pump check valve gets old - and you have to repressurise before you crank. This can be fixed without getting into the fuel tank through the addition of a fuel pressure check valve - I believe it's a BMW part and it's actually reasonably priced. If you search up <"fuel pressure" BMW> here you may be able to find it.

4) Your CKP is getting old and not generating a full-strength signal, or there is a wiring fault that is reducing signal strength before it gets to the ECU (Engine Control Unit.) There was a recall on this - I may have a copy (somewhere...) and I'm sure it can be found online. It would allow you to wire the CKP more directly to the ECU, thus eliminating a couple of connexions (read: contaminant intrusion points) between the CKP and ECU.

A far as the check valve on RENIX motors.. it is hit and miss, but for like 10$ its not bad. Usually have to order the part tho. I have a spare that I was going to install in my friend's XJ if anyone wants to buy it.

 

[jeepinwi]

Regarding the BMW fuel check valve, I installed one on my wife's 00 XJ because she was getting long crank times to start the engine. It worked great for a couple weeks, then the fuel pressure regulator on the fuel rail began leaking. Ended up doing the right fix of replacing the fuel pump/regulator assembly. The BMW check valve is simply a bandaid.

 

[Johnnie Walker]

Regarding the BMW fuel check valve, I installed one on my wife's 00 XJ because she was getting long crank times to start the engine. It worked great for a couple weeks, then the fuel pressure regulator on the fuel rail began leaking. Ended up doing the right fix of replacing the fuel pump/regulator assembly. The BMW check valve is simply a bandaid.

For some yes, but I know a few who have had great success with them. and for 10$ you cant go wrong. For the newer (97+) XJ's I may see how it would be temp. But on RENIX/OBDI I see it working well.

 

[SilberCobra]

Yep - there are a few causes.

1) The RENIX control system is designed to not fire FI or spark until it gets 300rpm at the CKP (CranKshaft Position seensor.) It looks for valid CKP/CMP (CaMshaft Position sensor) signals, but it can "guess" if it gets no valid CMP. I've verified this experimentally - it will sound like the timing is off, but will smooth out once it catches.

2) This means that as, say, your battery or starter motor get weak, they won't get your engine up to 300rpm as quickly. Also, the OEM mains are a bit undersized - reports from the field show that upgrading your mains cabling can (and usually do) help to get your rig to start faster.

3) The fuel pump check valve gets old - and you have to repressurise before you crank. This can be fixed without getting into the fuel tank through the addition of a fuel pressure check valve - I believe it's a BMW part and it's actually reasonably priced. If you search up <"fuel pressure" BMW> here you may be able to find it.

4) Your CKP is getting old and not generating a full-strength signal, or there is a wiring fault that is reducing signal strength before it gets to the ECU (Engine Control Unit.) There was a recall on this - I may have a copy (somewhere...) and I'm sure it can be found online. It would allow you to wire the CKP more directly to the ECU, thus eliminating a couple of connexions (read: contaminant intrusion points) between the CKP and ECU.

Thank you for the help.
Silber