i have a 1990 xj 4 dr 4.6. it tends to overheat wen its warm outside. in 4wd it almost reaches 230. i did a t-stat change, radiator flush, cold air intake. still drives hot. also has trouble starting. turns over fine but doesnt seem like its getting enough fuel. anybody know wut to do to help these problems?

Thanks

 

my jeep always takes 5-7 sec to start every time. with the over heating thing...ditch the clutch fan and get duel electric fans.

 

Maybe your clutch fan is bad, I would start there.

 

so an electric fan is better than the clutch fan? cuz the clutch fan is always spinning wen the jeep is on..

 

ditto....ditch clutch fan...puts useless load and weight on engine...run dual/tri fans in push/pull formation at 3000+ cfm with a manual over ride switch... here's a good one... http://www.ffdynamics.com/cherokeeB.html

take a look around here for overheating tips.... http://www.lunghd.com/Tech_Articles/..._Diagnosis.htm ....here... http://www.lunghd.com/Tech_Articles/...iagnostics.htm ...and here for more.... http://www.lunghd.com/Tech_Index.htm

 

Your next best upgrade would be the electric fans. You have flow through the radiator (as long as you know your water pump is good), now you need to cool what's in it better than the stock prop.

 

1) 4.6L - stroked?

2) Chances are good your fan clutch is shot. Most vehicles see them as "lifetime" parts or close to it - on the Jeep, they're good for about five years. Write the date on the new one when you put it in, since you'll forget after about a week that you'd done it. It's a good habit for maintenance parts in general...

3) You may be losing the seal at the "volume tank" up in the pax rear corner of the engine bay. You can get a new one - with cap - from Morris 4x4 Center for a decent price. Change this every 5-6 years as well. Changing this tank offers a good opportunity to flush the system - which really should be done every 2-3 years anyhow, and the coolant replaced. If you don't know how long it's been, use the two-part Prestone flush (oxalic acid and a neutraliser,) and follow the directions exactly with the following addition - after the neutraliser is flushed through the system, do an extra flush using plain water. Make sure you drain all of the water out of the system, and cut your coolant with distilled or Reverse Osmosis-filtered water.

4) Adding a bottle of Redline's Water Wetter won't go amiss, either. It's a surfactant, which increases the contact between the water and the internal surfaces of the cooling system parts (improving heat acceptance and rejection.)

5) For your "not getting enough fuel," could you describe it a bit more? I'm inclined to think it's the standard "check valve in the fuel pump going out" issue, but I want to be sure. The problem mentioned can be easily tested for with no equipment - when you go to start (especially cold,) turn the key to ON and leave it there for 4-5 seconds. Turn it OFF, turn it back ON for 4-5 seconds again immediately. Then crank it around to START. If the engine catches quickly, the fuel pump pressure check valve is going out - I seem to want to recall a low-buck BMW part negates the need to change the fuel pump itself (information should be findable at NAXJA.org with a brief search.)

If the engine cranks slowly, you either have a battery going out or the connections are getting shonky - check, clean, and service PRN. NB: the RENIX engine management system will not fire the ignition or fuel injection until it reads 300rpm at the CKP, and it wants a valid SYNC signal from the CMP (it can "guess" without the CMP, but it will not start without the CKP signal.) Moreover, the stupid little ground strap between the engine and chassis - driver's side rear of the cylinder head - gets contaminated and degrades the chassis ground with age. Most sensors are grounded to the engine, and the ECU is grounded to the chassis. There is no other chassis ground (which is why I usually suggest adding one from the battery directly to the chassis. Use min. 8AWG wiring) and cleaning the chassis contact points for all grounds down to bare metal and applying a corrosion inhibitor on assembly. Grounding through paint is also a silly notion - but it saves a buck or two a frame, and that is enough for a beancounter.

 

ok 5-90.. thanx for the help in ur post. as far as the not getting enough fuel situation, wen i go to start it wen its cold it cranks about 10-15 times before attempting to start and i stop and about 5 second later i try about and its starts afte about 2-3 cranks. also it WILL NOT start wen its hot. wen im out on the trail and its warm outside it gets really hot in 4wd and if i turn it off it wont start for about 20 mins until its around 210. also wen its hott on the trail, it wont start if the jeep is at an incline so thats why i say i think its lacking fuel. but if the front is at a decline it usually starts fine even wen its pretty hot.. and i checked today to see if my electric fan worked and i dont believe it does. i painted a mark on the fan and the plastic and it didnt even move and i drove about 30 miles. so im sure that doesnt work. i will b getting to new electris fans tomorrow and putting them in. also how should i wire the fans? electrically to a switch inside my jeep? cuz the wires that r connected to the fan now dont seem like they r live wires so im going to check that out tomorrow as well. Thanks for ur help bro!

 

OK - for hot start problems, what you are describing is a classic "heat soak" problem. Question - do you still have the OEM fuel injectors in place? You can tell if you do by simply looking at them - the lower body is steel, the upper body is plastic (later pieces - and the "upgrade replacements" often used - have a fully plastic body. The two parts are ultrasonically welded vice crimped.) Having OEM RENIX injectors can be a pain in more ways than one - not only are the RENIX injectors susceptible to heat-soaking, but that crimped join will start to leak after a while (and the fuel rail and intake are right over the hot exhaust manifold!)

You can search up "Heat Soak" on various Jeep boards to look for potential solutions, but if the injectors are original I'd just replace them!

The cold start issue sounds like the loss of fuel system pressure overnight (the check valve is meant to prevent this, mostly. It's also supposed to help keep fuel from draining back from the pressurised side of the system.) Search at NAXJA for the BMW part, since I don't know the number offhand. That check valve may then be installed between the fuel tank and the fuel filter in a matter of a few minutes without any trouble.

The e-fan issue is separate, naturally. Here's a (farly) short course...

1) The electrical auxiliary fan is wired up in a Logical OR circuit, where it will turn on IF the air conditioning is turned on OR the thermal fan switch (driver's side radiator tank) closes due to temperature (OR both - which is true for any Logical OR situation. The statement is "true" if any one more more of the conditions are met.)

2) The e-fan is wired up through a relay on the driver's side fender liner, about a foot back from the front crossmember and just below the hoodline. This is the relay that gets triggered if either/both of the conditions are TRUE.

3) This relay turns on, which sends power to the fan leads, and makes the fan run.

Now:
- If the fan motor proper is shot, it doesn't matter how much power you send it. Motor windings usually "fail open" - so a test with an ohmmeter will show infinite resistance on all ranges.
- If the relay is shot, the "Logical OR" statement cannot become TRUE. The relay is the "statement" that becomes TRUE if EITHER a OR b (OR both) become true.)

Course of action:
- Test the fan motor. Either supply the fan motor with battery power directly for a short time (using min. 12AWG test leads, and make sure you don't touch the clips together!) to see if the fan starts turning. If not, replace (the 1997-up fan will move more air, but usually requires a terminal change to effect the swap. Easy.)
- Test the relay. Here's how:
-- Put an ohmmeter across pins 85 and 86. According to the new DIN relays I've got handy here (made by Bosch,) you should see 90 ohms +/- 5-7% or so. This is the coil for the relay - it also usually "fails open" and shows infinite resistance on all ranges. If it fails, replace it.
-- Clip one lead to pin 30, and the other to pin 87a. Should read zero resistance (these are the "Normally Closed" contacts.)
-- Move the lead from pin 87a to pin 87. It should show infinite resistance (these are the "Normally Open" contacts. The two sets of contacts will reverse in the next step...)
-- Clip one side of a 9V battery to pin 85, and the other to pin 86. You should feel and hear a small 'click' in the relay when you do this. You should also see the resistance between pins 30 and 87 go from "infinite" to zero.
-- Leave the battery clipped on for a minute - move the pin 87 lead to pin 87a. Should show "infinite" resistance.
-- If the relay fails any one of these steps, replace it.

As a final check, make sure that the socket corresponding to pin 30 on the relay has power (battery voltage) with the key ON - if it doesn't, you've got a wiring fault to find (or a blown fuse or fusible link.)

 

duel electric fans and hood vents. or just upgrade the cooling systen from like a 94

 

injectors r not stock. its has 24 lb fuel injectors that wer replaced like a year ago. now as far as the electric fans can i just wire them to a switch inside and leave them both running at all times?

 

The only problem of running dual electric fans would be the alternator. You will need to upgrade to a 136amp or higher. What I do is turn the key but don't crank wait 5sec then crank it.

 

can i run the fans off my batteries? i have dual yellowtop optimas..