FigurativeGarbage

I've written some stuff on an early 90's 3.4L Camaro engine. I'm about to pick up the project again after a year on the backburner. I made wiring diagrams and such.

Seems to have fixed pump/baffle issue. I haven't seen anyone else do this, nor has it been suggested. I hope it works. In the image below, cut the sender guides on the tank wider (at 7 and 11 o'clock). At this orientation, the pump won't press into the baffle wall. I also was able to get the sock on with one hand in the tank. Had to walk away from it twice before I had an aneurysm.

Looks like I have a common issue: the baffle in the tank is in the way. However, it seems that if you turn the sender just a few degrees to the right, the pump will point straight down and sit in the baffle. This would require doubling the space for the guide tabs, but it seems easier than cutting the baffle (and compromising its function) getting a new tank, bending the sender, or getting a new sender. My hope is the gasket under tension keeps it aligned. It seems no one else has done this in the other threads. Also, the fuel gage is in the way when installing, so I have to partially disassemble the sender and reassemble it with one hand it the tank. I can do this, but getting the sock on the pump with one hand feels like a carnival game.

Looks like I'll go for the MTS JPSU-6P4.0. Seems like it will provide enough flow and PSI for the 3.4L. https://www.mtscompany.com/sendingunits.htm $39? Its like $65-$160 everywhere else: https://a.co/d/hePOZeq

Dropped the tank and pulled the sending unit. As I suspected, there's a hole near the rear grommet that is likely the source of water contamination. After I get a new tank, I need a fuel sending unit that will deliver 36-50 PSI to the Camaro engine. I prefer to do it in tank, but I'm not interested in figuring out a complicated custom system. I may do in-line so I can get this fired up this year. I'll need new fuel lines for the pressure in any case. Open to thoughts.

Spent some time this weekend sorting the original engine bay wiring a bit more. There are still several mystery connections to resolve (hanging outside of the cabin in the pic below). I removed the auxillery lights and relay for now. I also removed the fuel pump and what I think was the B+ latch relays as they look pretty corroded. I ordered a relay box and bus bar to help clean things up. I'll also relocate the electric fan relay the previous owner installed. Frustratingly, I found water in the passenger side cabin. I see in other posts this isn't terribly uncommon and is likely either the hood hinge seal or the blower/heater seal. I'm not wild about pulling the dash right now. Goal is to try and get the motor started soon.

It has those sections, for sure, but they don't have the illustrative diagrams that I found helpful as an amateur (pinouts, harness routes, etc.). If I'm wrong, let me know what page or upload (if you have have a chance). For example, white, yellow, and green run to the axle and I am guessing they are the 4wd actuator. Identifying these will take some time, but I suspect they are no longer necessary unless they run to the gauges. Points if you know what this is.

I removed the starter solenoid because the new starter has an attached solenoid. I'm thinking I'll keep the ignition relay. I removed the ICU/distributor (between the original fuses and alternator). The standalone wiring harness is largely thinned save for figuring out the C### connections. I need to clean up the remaining original wiring a bit more (A/C related, I/P to engine connectors, etc.). It is harder to find information on the 2.5L Comanche; the service manuals are not as thorough as the Camaro manuals I've been using for the engine (wiring diagrams for the instruments, headlights, etc.).

I can't seem to download this (link is a blank page). Can anyone re-upload it?

Cleaned up my hand-drawn diagram on Lucidity. I believe I found one solution to this set up: a VSS dual bypass (Dakota Digital SEN-01-4280). This allows the mechanical signal to go to the dash and converts an electronic signal to the ECU. I believe the B28 Buffered Speed Output sends to the dash and therefore can be removed. I'll next make a list of the C100-230 wires that need to be resolved (fuel pump relay, etc)

I'm currently working on a standalone ECU harness. I’ve de-pinned around 17 wires from the ECU connectors. Most of these were related to automatic trans and AC functions, which are unnecessary for my standalone setup. (not my photo, but used for initial reference) (one of the Camaro manual diagrams) I've been looking at connectors C100, C210, C220, and C230 that connect to lights and the body harness. Example: the C220 alternator connector powers the dash. I have a GM VATS bypass from Timers. I need to figure out speedometer and fuel relay wiring. (The C220 only has two wires in it right now, and matching connector. I'll need to figure out the clutch anticipator.) I also discovered a mystery component with brown and black/white wires that seems to be tied to the oil level sensor area (it has some kind of recessed button that clicks when pressed). The actual oil level sensor connector nearby has two-black-wires. I'll trace the wires back for both if I have to. (Manual reset button? Diagnostics? Kill switch? Jetpack handheld ignition control?)

I got them from my neighbor. I'm sure you're right. Appreciated, but its okay. The original ones are on now. Mostly an aethetic thing anyways.

Looking at the clearance, I think modifying the pan was unnecessary. Maybe other the other builds noted the issue had different set ups. See the attached photos; one may appear upside down, but you can see there's a great deal of clearance. In hindsight, I would have installed the engine without a pan and check the clearances after.

It's okay, they were aftermarket aluminum valve covers. I kept the original covers just in case. Glad I did.

By December 2023, I had the 3.4L installed and was bolting in the exhaust manifolds. I broke a bolt in the cylinder head and I took the head off to have it professionally drilled out. I was horrified to find the cylinders were full of rust beyond what could be ignored of fixed with steel wool. The machine shop also tested the head: warped. I bought remanufactured heads from OReilly's for roughly $400 and paid $2k for the machinist to bore the cylinders, deck the mating surface, supply new pistons and bearings, and polish the crankshaft. I got the engine back around early spring and rebuilt the engine. At this point feel like I've replaced nearly everything on it. Countless trips to Ace to find the right bolts. The total cost has far exceeded what I would have spent on a crate engine, but then I wouldn't have learned how to install Helicoils in a newly machined engine block near the cylinder head mating surface. (Unsure what happened with area after spending all that money machining the mating surface) Now I'm on to wiring, which everyone has told me will be the most difficult part. I've pulled the old ECU (near driver's right knee if anyone is doing this) and attached harness. I've figured out all but one or two connectors on the new harness. My understanding is I need to delete the A/C (I deleted and replaced with a dummy pulley) transmission (this is a manual) level sensors and coolant temp sender (will be wired to the dash) C100 &C210-230 connections to non-engine Camaro harnesses. (I cracked the aluminum valve covers I so carefully painted red; they may not have been 100% compatible or I just over torqued) I will also need to figure out a new relay/fuse system. And figure out the antitheft bypass. And install the fuel pump, line, and power. And finish the coolant system. And power steering. And vacuum tubes. And drop the tank to figure out how this all started. I've found CC users to be genuinely helpful in my other posts and in the guides I've reviewed. I document my struggles and progress should this be of any use to someone or if anyone has suggestions moving forward. Cheers.

I've posted about this truck in other threads, but my last update was about 18 months ago. Another user had then suggested I start a project thread to document the build. Background We bought an electric commuter car in April 2022, so I figured I didn’t need my newer Subaru for house projects or hauling the paddleboard on weekends. In August 2022, I bought a 1986 Jeep Comanche with a 2.5L engine and a 4-speed manual transmission. The previous owner made a few modifications, like an electric fan with some questionable wiring, replaced parts of the interior with components from a Chevy Silverado, and an odd sliding motorcycle rack bolted to the bed. I had never done any work on a vehicle before, aside from topping off wiper fluid. I paid a mechanic to work on the differential and fix the missing passenger seatbelt bolt. I wasn’t planning on turning this truck into a showpiece or a rock-crawling off-roader, but I did notice 2.5L engine struggled to keep up on the highway, maxing out at about 65 mph during my commute. Not long after I bought the truck, I started noticing the idle getting rough. About two months after buying, the engine quit working altogether. A neighbor found that the fuel coming out of the injector was not flammable. Given that the rainy season had just started, I figured rainwater invaded the fuel tank, either from rust or wild drilling when the previous owner install the motorcycle rack. My neighbor said I should consider replacing the injector with a carburetor, but he also mentioned that he had a 3.4L engine from a 1994 Camaro sitting in his garage. I knew from this website that some owners swap 2.8L engines for the 3.4L from a 1993-1995 Camaro. He said I could have the engine for free. That was two long years ago. I understand that this build would be more difficult because I couldn't just pull compatible parts as is the case with a 2.8L. I cleaned the 3.4L, removed the 2.5L and accessories (without knowing what most of it was exactly), had a welder modify the oil pan to make sure it would clear the differential, replaced the clutch, machined the flywheel, I even had the welder fabricate custom engine mounts (I got tired of searching for them after a salvage yard crushed a car I spent a precious Saturday pulling the rusted accessories off). I bought a new upper intake manifold, exhaust manifolds, an ECU from ebay (hopefully coded properly with the VIN I gave them), had a salvage yard pull an engine harness from an automatic 3.4L Firebird, new accessories, accessory brackets from ebay.

Sorry, I haven't logged in to CC in a long time. In hindsight, I suspect the unmodified pan may have had enough clearance without modifications. I'll see if I can get you a pic at some point. For now, I'm going to document this project on the projects thread as eaglescout suggested.

Got the flywheel on, replaced the rear main seal, clutch, release bearing, and slave cylinder (old one pictured below...). The hydraulic line was stuck/mangled, so that will need to be replaced too. With much difficulty, my neighbor helped me get the engine connected to the transmission. The custom oil pan was still difficult to maneuver around the differential and sway bar. I ordered Brown Dog mounts for a 2.5L two days ago. My plan is to mockup some cardboard engine brackets for a weld shop to fabricate. Then order accessories, accessory brackets, replace missing transmission bolts, exhaust, air intake, delete the charcoal filter.....then wiring and world peace.

I bit the bullet and got the Camaro oil pan custom cut to clear the differential. Got some aluminum valve covers from the neighbor and painted them rustoleum red. Replaced the rear main seal and need to replace a few studs (stripped or missing) from the hardware store tonight. New flywheel bolts come in tomorrow, then I can install the 2.8L S10 neutrally balanced flywheel I have and a 2.8L clutch kit from M-PACT. I was worried it wouldn't mount to the 2.5L 4 speed transmission, but it appears to be fine.... Engine is on the hoist and otherwise ready to see how it aligns with the existing mounts. I'll need engine-side brackets, hopefully picked from 2.8L Comanches in a junkyard an hour away.

The 2.8L frame brackets look the same as the 2.5L brackets. From this decent thread: '86 Comanche Long bed, Slow build... | Expedition Portal

I think I should definitely get new mounts based on the condition of the current mounts. Rubber dog sells two different mounts for the 2.5L and the 2.8. Here's the 2.8L And here's the 2.5L You can see the passenger mount bolts just a bit differently, although I'm not sure why. Currently I have the 2.5L frames/brackets, but will they put the mounts in the correct position for the 3.4L? If possible, could I see and/or buy the 2.5 frames? Otherwise, Brown Dog thinks I might need to custom fabricate frames.

Here's the passenger-side mount. It is different from the 2.8L mount, as the 2.8L mounts appear to be interchangeable (same on both sides).

I've been learning a lot and trying to move this along each week. I'm attaching many photos, but the big question is the last one: I don't know if the engine mounts are the same as a 2.8L. I can order those cheap or get rubber Brown Dog mounts for like $200 with the bolts, but I can't seem to find the frame mounts. I have heard the mounts are the same between the 2.5L and the 2.8L. current engine bay after removing the engine. Two engine pans resting on the side. old 2.5L New 3.4L side (from 1994 camaro) 3.4L rear 3.4L after cleaning and painting 3.4L oil pan next to the 2.8L engine pan I bought. 3.4L oil pan won't clear the differential, while the 2.8L won't mount to the engine because the timing cover is different (flat instead of rounded (see the blue gasket in prior pic)). I may have to buy another one from ebay for $130 (asking price is $172). New engine with aluminum valve covers (will clean and paint later), intake manifold. Interior after ripping out carpet and bench seat. I'll eventually go with Lizardskin paint, but I need this driving first. Driver's engine mounts (original 2.5L). I need the PS pump, alternator, starter, and brackets, which I can either order new, or strip from my neighbor's S10.

Does the exhaust header and y-pipe come from the 3.4L camaro? Cuz that's what I did (new, wasn't cheap). However,@JeepcoMJ said: The parts you will be saving from the original 2.8 will be: 1. Exhaust manifolds and y pipe...(continued) I'm on my big yearly stay-cation until January 2nd, so I'm trying to get as much of this sorted as I have time for it. I have ordered my fuel rail, ordered an engine harness at a nearby scrape yard today (I'll pull out the automatic wiring), ordered fuel pump. Have sensors, have the motor, have upper manifold, have flashed ECU. Still need air intake, flywheel, 2.8L oil pan, oil pressure cut-off switch?, water pump?, alternator?, valve covers?

It's a manual. I heard manuals can accept computers and engines from automatic donor vehicles, but not vice versa. Correct me if I'm wrong. I found an automatic 94 Camaro in a junkyard near me today. I'll have to see if I can get ahold of them. Used 1994 Chevrolet Camaro Air And Fuel Throttle Body Throttle Va (hollanderstores.com). Maybe I bought the manifolds and oil pan too soon if I can get it cheaper from them, but I like idea of getting the harness, ECU, etc from one vehicle. I think that might solve the ECU VIN issue if it comes straight from the junkyard rather than refurbished like some of the ebay sellers?