• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Renix no start.

V

VAwheeler

NAXJA Forum User
Location
SE Virginia
The first page looked wierd without a Renix no start issue being there, so I figured i would throw mine out there and see what you guys had to say. I have done my fair share of searching and am just trying to see what it is that I am missing.
hastahastahasta

1990 4.0L just rebiult, manual trans.

I have not been able to get my jeep to start since the rebuild and now I feel like beating my head against a wall.

So far I have checked to make sure that I am getting a spark, and I am. I checked to make sure that I am getting fuel, I have 39 lbs when cranking. I put new fuel injectors and I am sure that they are operating properly because the plugs are coated with fuel when I pull them after trying to start it. I checked the wiring to the injectors to make sure that the correct injector was firing at the correct time and everything is fine there. I have checked timing no less that a dozen times, both by pulling the distrubuter cap and rotating the engine until TDC and making sure the rotor was pointing at the #1 plug wire; and with a timing light. I also took the advice of others on here and gound off the tabs on the distrubutor so that I could try and rotate it a few degrees while a friend tried to start it in case I was off on timing by a tooth or two.
(Along with the rebuild the distrubutor, rotor, cap, button, wires, plugs, and coil were all replaced.)


I checked the CPS and I am within specs at 232 ohms. I just finished checking the TPS and it did need adjustment but even after it was corrected it still wont start. After the adjustment it is reading 4.85V between the A and B connectors and .82V between the B and C connectors, for a ratio of .169.

I have checked to make sure that the ground strap that goes from the firewall to the intake manifold is clean and attached securely. I have also checked the ground that attaches to the passenger side of the block.


Are there any other sensors that are needed to ensure the engine will start that I have not listed? When it cranks it seems to be cranking real slowly. But, all of the neccasary components to get it to start seem to be there. I am out of ideas of what the issue could be.


EDIT: I found this statement in one of the other threads but have no clue what bolt he is refering to:

MJmk said:
Get your INCH/LB torque wrench out, and make sure the bolt in the center of the big connector behind the brake booster is tightened to the correct spec, 70 inch/lbs.
Click to expand...
 
Last edited:
Are you sure #1 was a TDC on the *compression* stroke when you checked? It's an easy thing to miss.

The bolt is the one holding the firewall harness connector.
 
Yes I am sure it was a TDC. I held my finger over the hole for the spark plug until I could feel it wanting to blow my finger off. Then I used a wooden dowel to measure when the piston came to its top most position.


I am about to go out and check the bolt, but I am confused as to why a bolt holding the firewall harness connector would affect the start. I guess I will understand once I go out and find it.
 
How's the battery? It should be really whirling the engine over, not cranking slowly. I assume that compression check has been done since the rebuild as fuell + ignition + compression = start. Test camshaft position sensor located in the distributor. I think the MAP sensor can be a factor in the no-start. You replaced a lot of stuff; it could be something as simple as a connection somewhere. Retrace all your steps and get that meter out! Let us know what you find out....
 
Hey! The bolt is only on the '87 and '88's IIRC (models with the C101 connector) so you probably won't find it on yours.

I would agree with the MAP sensor test, and make sure the vacuum line is installed corrrectly.

Seems if you have spark, you should have some kind of fire with fuel in the cylinders. Make sure you have a good battery and it's fully charged. Nice blue spark? Fresh fuel? (Curious why you have spark and it's not igniting) Any chance you're not getting any airflow through the engine, like restricted air intake, or plugged exhaust system?
 
birchlakeXJ said:
How's the battery? It should be really whirling the engine over, not cranking slowly. I assume that compression check has been done since the rebuild as fuell + ignition + compression = start. Test camshaft position sensor located in the distributor. I think the MAP sensor can be a factor in the no-start. You replaced a lot of stuff; it could be something as simple as a connection somewhere. Retrace all your steps and get that meter out! Let us know what you find out....
Click to expand...

The cam shaft position sensor that is located in the distributor... Could it also be called the sync signal sensor?
That is all I could find in the FSM that seems to be what you are talking about. I went ahead and tested that last night and I was only getting a reading of 2.xxV when the FSM said that I should be getting 5V. I am not sure that this is a problem yet b/c I was in the process of charging the battery while I was testing and I think that the weak battery caused the low voltage. I am going to check again tonight. I have a spare new distibutor sitting in the garage and I may just swap it in to check.

MJmk said:
Hey! The bolt is only on the '87 and '88's IIRC (models with the C101 connector) so you probably won't find it on yours.

I would agree with the MAP sensor test, and make sure the vacuum line is installed corrrectly.

Seems if you have spark, you should have some kind of fire with fuel in the cylinders. Make sure you have a good battery and it's fully charged. Nice blue spark? Fresh fuel? (Curious why you have spark and it's not igniting) Any chance you're not getting any airflow through the engine, like restricted air intake, or plugged exhaust system?
Click to expand...

Thank you for the verification on the bolt. I was looking all over the place last night and could not figure out where it was.

I have double checked the MAP sensor input/output and I have 5.01V between connectors A and C and have 4.8V between connectors A and B. The FSM calls out a spec of 5.0V +/-0.5V, so this is within specs.

I do have fresh fuel. There was about 2-3 gallons of old fuel in the tank. So I disconnected the fuel line just before the filter and used the fuel pump to drail all of the old gas out. I then put a new fuel filter in, reconnected the line and poured 5 gallons on new fuel in the tank. I had planned on running the jepp for 200-300 miles and then changing the filter again to ensure that any junk that was left in the bottom of the tank had been cleaned out through the filter. I feel confident that the filter has not gotten clogged due to me having proper fuel pressure.

The battery may be the problem. I left it on a 2a trickle charge all day and my charger is now saying its charged 100%. I will be going out there in just a little while and trying again.

Bugboy said:
does it try to fire at all?
Click to expand...

I would estimate about 90% of the time it doesn't even sound like its trying to start. The other 10% of the time I can get a small "cough" out of it, but its not anywhere close to what I would consider close to starting at any point.
 
i had this problem with a boat engine once and it was because the plugs were fouled(soaked) by fuel from trying to start it so many times. took the plugs out and burned fuel off with a lighter. the engine was carburated so im not sure if it would cause the same problem.

the bolt the other person is refering to holds the wiring harness in the engine bay to the back of the fuse block. its nearly impossible to see because the top part of the harness is blocking the view. if you didnt mess with it i doubt thats the problem.

have you tried spraying starter fluid down the intake? if the engine spits and pops, it could be a fuel issue or timing issue.

as for timing issue, i found the easiest way to find TDC of the #1 cylinder is by the harmonic balance. the replacement harmonic balance i put on my 89 has an indent on it and when the 1 cylinder is at TDC, the indent will be at zero on the timing scale.
 
i have definately had fouled plugs due to trying to start a vehicle too many times when something was broken, then u fix the problem and it still wont start all cause u forgot to clean the plugs after the repair...i usually pull them out and clean them of with brake cleaner, dry em off and put em back in...i would try that before u go looking to deep for something simple
 
VAWheeler, sorry but I didn't see it anywhere, are you getting spark? There was a modification the jeep would do with the CPS to bypass all the funny connectors and run the CPS directly to the computer. Have you checked your signals at the connector going into the computer? I have had a wire corrode to the point that intermittently failed, then one day it no longer worked. I had to replace several wires on the engine bay side of the firewall connector due to excessive corrosion.
 
If the injectors are cycling, you have fuel at the fuel rail (under presure) and it's sparking, something is going to happen even if it is an occasional pop.
The starter has to be cranking at a pretty good clip for a successful start.
Pull a plug open it up to 0.060 or so, ground it and crank the engine over. If you get a spark, is it blue or yellow? Best to use a rubber glove and not to hold your crotch on the fender when trying this, odd paths to ground can leave a tingle in your hootus.
Cleaning the plugs is good advice along with making sure you have a good strong spark. Strong sparks are crisp, usually blue or blue white with maybe a little yellow, you can often hear the pop; weak sparks are yellow and when very weak sometimes actually splash on the plug electrode.
The low voltage at your cam position sensor isn't good, this can indicate a short in the 5 volt supply someplace, usually an upstream sensor short.
 
8Mud said:
Best to use a rubber glove and not to hold your crotch on the fender when trying this, odd paths to ground can leave a tingle in your hootus.quote]

:roflmao:

8Mud, never quite heard it described like that before but for anybody that has had it happen to them, I think you're DEAD ON!!!
Click to expand...
 
dbxtr3 said:
Will it start if you spray starting fluid into the intake.

Maybe fire upfor a few seconds until it burns up the starting fliud then die.
Click to expand...

I tried spraying starting fluid directly into the throttle body and it still wouldn't start. It would throw the occasional backfire up into the air though.

8Mud said:
If the injectors are cycling, you have fuel at the fuel rail (under presure) and it's sparking, something is going to happen even if it is an occasional pop.
The starter has to be cranking at a pretty good clip for a successful start.
Pull a plug open it up to 0.060 or so, ground it and crank the engine over. If you get a spark, is it blue or yellow? Best to use a rubber glove and not to hold your crotch on the fender when trying this, odd paths to ground can leave a tingle in your hootus.
Cleaning the plugs is good advice along with making sure you have a good strong spark. Strong sparks are crisp, usually blue or blue white with maybe a little yellow, you can often hear the pop; weak sparks are yellow and when very weak sometimes actually splash on the plug electrode.
The low voltage at your cam position sensor isn't good, this can indicate a short in the 5 volt supply someplace, usually an upstream sensor short.
Click to expand...

There is a blue spark coming from the plugs even with them gapped to 0.030".

I too am worried about the low voltage coming from the cam sensor. I still haven't been able to get out to the garage the past couple of days to check to see if the voltage is in the correct range now that the battery has a full charge. I did however try to start it once with the battery being charged and it still wouldn't start. I will be able to get out to that garage for a little while this evening and I will be sure to check it again.


Other than the cam sensor giving me a wierd reading the first time, I am not sure what else to check. I have the pin out diagram for the ECU and I am going to try and check all of the voltages directly at the ECU to ensure that there is not a short in the wiring somewhere.
 
This sounds so much like a distributor indexing problem to me. I had issues after the engine was rebuilt in my 90 trying to get the indexing correct. It turned out to be a improperly marked "new" harmonic balancer. The mark was about 20 degrees off and had me setting the dizzy off by a tooth. Its when I checked TDC at #1 and made sure I was at the top that I finally got it right. I do not trust the timing mark on a HB anymore! I also had to cut the tab on my dizzy and move it some to help dial in the injector timing some to smooth the engine out.

Are you 100% sure the cam is timed to the crank properly and also are the injectors hooked up properly?

If you werent on the other side of the state and 5 hours away I would stop by and give you a hand, 2 gear heads are better than one!
 
got fuel and spark and distributor timing is good, than i would look to see if the timing chain gears were installed correctly.
 
You must log in or register to reply here.

Similar threads

S
1998 XJ no start - No fuel pressure
Replies
11
Views
2K
sjx40250
S
E
CA smog issue "Minimum voltage not detected"
Replies
13
Views
982
Johnnie Walker
Johnnie Walker
Ecomike
87 Renix XJ No fuel, No brake lights, cranks fine
2
Replies
27
Views
855
Anak
Anak
O
2000 XJ Failed Colorado Emissions high CO
2
Replies
27
Views
2K
Ken M
K
A
Auto locks issue
Replies
4
Views
292
Saudade
Saudade
Back
Top