jamcomanche

Amazon has dorman elbows that look the same size as the 5/32 plastic lines. When I replaced mine I ordered 5/32 and 7/32 silicone vacuum tube with some T's and rubber caps and made my own redneck elbows

I can't tell you how fun it's been... haha! As far as getting the truck to start and run goes, I've made NO progress at all. But.. as of today I've replaced all of the vacuum lines according to the 87 TBI diagram with a couple modifications to get rid of the thermostatic air cleaner thing. And the PO put a 2 port vacuum ball in it from a 4.2L that routes to the HVAC controls... Needless to say, I spent a LOT of time looking cross-eyed at diagrams. Serviced the Throttle Body with new seals, gaskets and diaphragm. MAP sensor with key on reads 4.8v output and drops to ~2v when the engine initially fires and chokes out. New EGR valve installed. Tested the solenoid and it seems good. But still... immediately dies after the initial rev when it fires up. TPS reads 4.71v at WOT and 0.17v with throttle closed. I am going to try to get the closed voltage up and see if that makes a difference. If not... going to check pressure at the throttle body I think. There is a chance the diaphragm I put in could be bad since the truck would idle before I serviced the TB. But from past experience, I will probably go around and check/probe all of the related wiring harness connectors.

I made a post recently looking for a good source for replacement EGR Valves for my 87 2.5 - I was under the impression that these valves could be tested simply by applying vacuum to the connection on the valve to check for leaks and proper valve function. After returning a few valves that wouldnt hold vacuum, I contacted Standard Motor Products (one of the manufacturers of replacements for the OEM 53002483 valves) and felt pretty dumb after I got some clarification on the specifications. Renix 2.5 EGR Valve (86-90) OEM Part #: 53002483 Replacement/Interchange Part #: EGV580 Type: Positive Backpressure Valve Operation A positive backpressure EGR valve is a vacuum-operated emission control device that uses exhaust pressure to modulate exhaust gas recirculation. It remains closed at idle, opening only when engine load increases. This design prevents engine hesitation and stalling by ensuring EGR doesn't occur during low-load operations. - Low Backpressure (Idle/Deceleration): At idle, exhaust backpressure is low. The internal bleed valve opens, bleeding off any engine vacuum that is applied to the main valve. Because the vacuum escapes, the EGR valve stays closed. - High Backpressure (Acceleration/Load): When you press the gas pedal, exhaust backpressure increases. This force pushes the pilot valve closed, sealing the vacuum bleed port. As the vacuum builds and holds, it overcomes the main control spring, pulling the EGR diaphragm up and allowing exhaust gases to recirculate into the intake manifold. Testing Set parking brake, place M/T in neutral, A/T in park. Start and warm engine to normal operating temperature; increase idle to, and hold at, 2500 to 3000 RPM. Disconnect vacuum hose at EGR valve. Check for at least 5"-8" of vacuum at this point. If no vacuum, check source including all hoses and vacuum controls (e.g. ported vacuum switches, control solenoids) To check EGR operation, bypass EGR solenoid (when used) with appropriate tubing. Using thumb, disconnect and plug vacuum hose at EGR valve. When removed, look for downward movement of diaphragm (can be seen through housing openings) and listen for a slight increase in engine speed. Reconnect vacuum hose. Diaphragm should move upward and engine speed should decrease slightly. When engine speed change and diaphragm movement occur with vacuum hose removed or installed, EGR is operating properly. If EGR solenoid is used, remove bypass tubing and reconnect. NOTE: Use only the instructions listed above to test the replacement valve. Due to its design, an off-car, bench test cannot be performed with a hand-held vacuum pump.

Bumping this again. Received another SMP today from O'reilly that was also defective. Looking for any help.

I'm doing a vacuum overhaul on my 87 2.5 and I'm looking for a quality EGR Valve. I've tried both Wells and SMP brands and the first 3 I've received didnt hold vacuum so they wouldnt open. I have 2 more on order hoping that eventually I'll get one that works. Does anybody have a direct link to a high quality EGR for the 2.5? It seems like there is absolutely no quality control on these parts from Wells and Standard Motor Products.

Thanks. Mine is an 87. But I discovered something else today. There are 2 vacuum lines that connect to the intake manifold. one of them is routed to the EGR solenoid over on the passenger side, and if I disconnect that line the engine idles really rough but i can leave the MAP vacuum connected. When I have both connected, it won't run. I looked at diagrams today and my vacuum system is a mess. The EGR has been connected to a vacuum port on the throttle body cap this whole time, and diagrams show that it's supposed to be connected at the solenoid. The one on the cap is supposed to run to the air box. SMH...

Thanks for the response my friend. Always appreciate being able to reach out to you. Thankfully I know it's not that. I've had the truck for about 6 years and I've done a lot of repairs - as well as a lot of correcting things the PO rigged together. The truck has always had it's good days and bad days. Sometimes it would run great and idle smooth. Other times it would idle rough and lack power. It has never produced a consistent power band and has pretty much always had fluctuations in power during acceleration. I'm not going to get into the entire list of things I've done to it. but as far as what might be related to my problem: I've replaced just about every sensor except for the CPS. Replaced the fuel pump last year (which was a blast because PO put an XJ sending unit in) This past weekend I replaced the timing chain, TPS and MAP. I have not replaced the EGR Valve I have not replaced the ISA. ( I asked about IAT in my previous post, but I meant to say ISA ) I have not closely inspected the vacuum system or replaced any lines. I've only made sure everything is connected. As of right now after a lot of searching, I am thinking (and hoping) there is a vacuum leak. There is evidence in my truck that things melt in that area, so I have some 1/8" OD stainless tubing coming in. I'm planning to use that and the existing rubber elbows to replace the small lines at the TB / Intake

@Divus 8 years later I'm here searching for an answer to the same problem. You still around?

@I_s2k I hope you're still here and found a solution. I am currently dealing with the same problem in my 87 2.5. Were you able to get your running? Maybe somebody else has seen this problem fixed and can help. I originally replaced the TPS thinking it was that because the truck would start missing and completely losing power under load. It had very rough idle. I could get it to rev no problem but as soon as I tried getting the truck to move it lost all power. At that point I thought the timing was off so pulled and replaced the timing chain (needed it anyway). Now the engine would start and immediately die, so I started going through the vacuum lines. That's when I discovered it would start and idle with the MAP vacuum unplugged. I've replaced the map and voltage checks out at 5.05v source and 4.85v out at idle with the vacuum unplugged. But as soon as I connect vacuum, it throttles down and dies. @eaglescout526 My TPS is set right now at around 4.75v at WOT. My understanding is that should cause a high idle, not a low idle. Do you know if that's correct? I'm trying to figure out what else might be causing the problem. I will try to get the TPS down to 4.63 at WOT like I've seen you mention in another post, but not sure if that would make a difference. Would the IAT cause this issue? My thoughts are if it were the IAT, the engine should start and idle smoothly with a little throttle, but it runs very rough that way. I will probably work on replacing vacuum lines next if I can't figure this out.

Thanks! It was a direct replacement? The wiring and outlet look different, if this is the one you are talking about The retainer bracket has a specific shape where it fits around the upper connections too.

This truck has all kinds of mixed parts on it. I should have learned by now to pull the parts before I order new ones. Thanks for the help! No rush on the info. I appreciate it whenever you can get around to it.

Also just noticed, the ebay listing for this unit says 13.5 Gal haha https://www.ebay.com/itm/184914035537

Thanks for the response eaglescout. Attached a photo (it's not my unit, but is the exact unit I have). Note it has the upper adjustable retainer bracket and EFPK-3210 pump. Mine is in much worse shape

Looking for some help on compatibility with my 87 2.5. My fuel pump is on it's death bed and I had ordered a replacement US MOTOR WORKS USEP7006 which did not fit in the existing sending unit at all. The sending unit on my truck has an upper pump retainer bracket, and appears to use the EFPK-3210 pump. Not only was the US Motor Works pump inlet shorter and wider, but the unit body was too short to be secured with the retainer. I've started a return for that and in the mean time ordered a complete JPSU-6P4 sending unit from ebay because I couldnt find the JPSU-6P2.5, but I'm trying to actually figure out what the best direct replacement would be. I have been thinking that the person who owned the truck previously may have used a Cherokee sending unit, which is not listed as compatible with the MJ anywhere... Here is what I've found JPSU-6 Notes: Does not have upper pump retainer Listed Compatibility: 87 MJ 2.5 using pump EFPK-3210 87 MJ 4.0 using pump EFPK-3204 JPSU-6P2.5 Notes: Does not have upper pump retainer Listed Compatibility: 87 MJ 2.5 using pump EFPK-3210 JPSU-6P4.0 Notes: Does not have upper pump retainer Listed Compatibility: 87 MJ 4.0 using pump EFPK-3204 JCSU-8790 Notes: Has upper pump retainer Listed Compatibility: 87 XJ 2.5 using pump EFPK-3210 JCSU-8790P2.5 Notes: Has upper pump retainer Listed Compatibility: 87 XJ 2.5 using pump EFPK-3210 Does anybody out there know: 1. if there is a reason the XJ units are not listed as being compatible with the MJ? 2. if the JPSU-6P4.0 will fit and work in the 2.5? 3. the best place to purchase one of these Thanks guys!

I originally had a 74 amp CS130 in my 87 2.5 and the bearing went out. Because I have some power fluctuations with lighting and an AMP installed, I decided to upgrate to a 105 amp 8137-3N from WAI Global. After I installed it and started up the engine, the voltage on my dash immediately went into the red at or above 18 volts. After a couple of seconds, it started cutting power repeatedly so I shut it off. I disconnected the output cable from the alternator and the connector and started her again to make sure it wasnt unrelated, and it read around 10-11v on my gauge. I started a return since I assume it's a bad voltage regulator in the alternator if it's pushing out that much voltage, but then I started thinking about what else could possibly be causing it. I ordered a pigtail replacement, which ended up being a 4-wire so I needed to figure out how to wire it up. Then I started looking at wiring threads and the pinout for the 8137-3N. My previous alternator only used the 2 middle terminals on the connector ( L and I/F pins ). When I look at threads about wiring up the CS130 with a 2-pin connection (this one for example), 99% of what I found said it should be using either S+I or S+L pins. Is there any reason I would need to change from the L+I connections to the S+I or S+L connection? Would that possibly cause the high voltage output? Or am I right in thinking it's just a bad regulator in the alt? Any help with this will also help me figure out the right way to wire in the new connector. Thanks!