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Hi All -

I recently picked up a '91 Classic 3.9 for $1K which is rust free (except for a small hole in the passenger floor pan against the tranny tunnel) but has been neglected for a few years and is in rough shape so trying to bring her back to life. I am new to Rovers and admittedly somewhat of a layman mechanic. I started with a tune up (plugs, wires, cap/rotor, belts) - I've also replaced a leaky PS pump & lines, and have 'cleaned' the MAF with spray cleaner.

I have a few issues I am trying to diagnose -

The motor will start, but:

1) The motor seems fine at idle, but when I apply easy throttle by hand or via accelerator, the motor chokes out and comes close to or dies out - if I apply heavy throttle, the motor will fight through the initial bogging and will successfully rev up, but when I release the throttle the motor will drop below idle RPMs and nearly dies before smoothing out again at idle. I have ordered a fuel pump relay and fuel filter as next steps I hope to tackle this weekend. I also have identified that the coolant temp. sensor wire is frayed, so ordered a new sensor and plug/harness to replace as I've read this can also cause problems. Any ideas as to what my issue would be otherwise? I assume the fuel pump itself is functioning somewhat normally as the motor will idle & run if I push RPMs past the initial bog.

2) At idle, the battery light on the dash will dimly flicker and under acceleration the dash light will strengthen. I have what seems to be the factory 85amp LUCAS unit in the truck - I ordered the up-rated 105amp unit from BPU, but I cannot get the BPU alternator to mount properly in what I believe is the stock bracket. It will mount into the bracket but then the alternator pulley is out of alignment with the PS pulley - I also can't get the new britpart alternator belt on the new BPU or old LUCAS unit. Anyone had these problems? BPU agreed to swap their 105amp unit with the BOSCH OE+ unit so I will give that a try. I will note that the battery is also brand new.

3) I ordered a new fan & fan clutch as the old fan was in rough shape and I have read these are prone to failure. I assembled the new fan clutch/fan and mounted the new set-up after replacing the belts - but now the fan seems to slightly hit the fan shroud in intervals every few seconds. I read perhaps one or more of the motor mounts are slack so that the fan shaft is not running on center. The motor mounts look tired as with most everything under the hood, but puzzling because the old fan appears to be exactly the same and did not contact the shroud.

I do have RAVE downloaded and have been following for maintenance - but I can't see to find anything directly relevant to these issues, so any input would help.

Much appreciated.

ILMRover
 

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1970-1995 Range Rover Classic
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81 Posts
Hi there,

I started my Land Rover ownership under similar circumstances as a DIY'er with a cheap '91 RRC.
My initial thoughts and opinions:

  1. Trouble running under throttle could be incorrect timing or timing advance. Timing should advance from 6° +/- 1° at idle to 8°-11° at 1600-2300 RPM; I believe the distributor vacuum advance hose should be disconnected...
    After rebuilding my engine, I was able to get the timing close with an $80 Harbor Freight timing light; mine ended up being set to ~12°. I also brought my RRC in to a local Land Rover specialist after the rebuild to double-check everything; the timing, base idle, and throttle body have to be harmonized for the engine to run properly. I haven't had any issues since.

  2. This is beyond my experience. Look into diagnosing the stock alternator before replacing it; I'm still running the original alternator without problems, but there's a likelihood that it's the wiring and not the alternator itself. In RAVE, Electrical 86 page 13 (808 in PDF), there's a really simple test to rule out the charging circuit. Eric the Car Guy also has a good video detailing this:

  3. My fan cover shroud was torn apart when I got it, probably because of the same problem. I run my engine without the it, just don't stick your fingers in there.
 

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1989 Range Rover Classic
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152 Posts
Good plan on replacing the old fan, mine exploded on the way to work one day, not a fun thing. After than I switched to electric fans.

Do you have an EFI/CEL light on? if so, the code could tell you if the stumbling issue is sensor related (throttle pot, MAF, IAV, etc). Replacing the IAV is a good idea regardless, they're prone to failing or getting stuck and, while a genuine LR one is ridiculously overpriced, there is a generic GM one that is the exact same part for a tiny fraction the cost (some searching on this site should find you the part number. )

In regards to the BPU alternator, I have the 140A version (which I believe is the same body) and while I had to modify the top bracket to get the belt to fit nicely, the bracketry lined up and so did the pulley, so I'm not sure where that issue is from.

Which coolant temp sensor are you referring to? There are 3 of them.
 
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