carb to injection progress

J

jcstuckinmuck

Daily Driver
Hi all, Onward with the coversion as you can see in the pictures this is the progress, so far carb removed and manifold, injection manifold on new gaskets, injectors are in with new seals,half of the harness is connected,so far so good and i have now the pinouts of the double relay.
The oxygen sensor port is fitted on the exhaust see picture and i have the new sensor and is ready to be installed

Now the fuel pump issue, can i use my carb tank, i was thinking of mounting the pump on the end of the sender unit and cut the pickup pipe and connect the pump in line, does this seem a good route!!. Second I notice the the blower motor for carb cooling fan has to come out as it would foul the meter unit, where does cooling fan go on the injected cars, picture would be helpful

Now the ecu pictured, is this where it sits on the injected cars,as the spare wheel will not fit in anymore, how is it done, aso any pictures
The cold start valve can be purchased not a problem, but the sensor in the head is as the temp gauge sensor is the only one in the head, also i know i need the thermostat housing too, which i dont have yet, can anybody think of anything else that i need to fit?
Please bear in mind iam in the uk and some of the parts need are hard to find here,many thanks john

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You can browse thru my adventure on a carb to FI conversion in this thread. If you skip ahead to this point in the thread, you can see where I started mounting the electronics in the spare tire well. To get the ECU in the right spot, the spare tire mount must be cut. The FI cars had a one legged mount that reached out over the ECU.
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Here is a thread on fuel pump location for an FI setup. Of course, I used an FI tank in my swap. My understanding is that you can use the carb tank, but it is not ideal. The FI tank feeds out of the bottom, so gravity is providing pressure to push the fuel towards the pump intake. With a carb tank, there will be a long suction draw by the pump to overcome gravity to suck the fuel up and out.
 
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I will add my experiences with some of this.

I did not fully follow your description of how you intend to mount/connect the fuel pump. But to keep it simple you can retain the existing (carb style) tank and use the existing fuel pick-up pipe (coming up to the top at the fuel level access plate). Granted it is not ideal but it will work fine. The Bosch EFI pumps are very capable of "sucking" the fuel up that pipe and feeding the injection. Especially if you are retaining a stock injection system (no larger injectors, aftermarket ECU, high performance engine, etc). You will need a pump designed for EFI; they have a much greater flow and pressure capacity. There are a ton of different Bosch EFI pumps out there, but honestly any of them will work (provided they are 12V and you can connect the fittings as needed). If possible try to get one made in the last 10 years or so. Bosch changed all of their pumps to a 'radial' design (internally), which is more efficient than the earlier 'vane' style. But either type will work. And these are robust pumps so a used one is very likely to still be good. You can test it on the bench if you like (message me for details).

There are a couple types of EFI fuel filters. Use the larger can size filter; it acts as a 'pulse' regulator to smooth out the flow. And the greater filtering capacity is preferred.

If you are using used injectors then you might want to test their spray pattern/flow rates first. Same with the cold start injector. A used cold start injector is likely to be fine (they only operate for a brief period and just need to dump in some extra fuel). But the main injectors are more critical. It might be worth purchasing new ones if your not sure about them. You can use lesser expensive ones from other applications to save some $$.

The cooling fan is different on the FI set-up. The blower is in the rear trunk and directs the air from the rear side of the manifold toward the injectors. In my opinion it is not really needed with EFI; the system constantly and heavily recirculates the fuel flow through the injector rail and that is sufficient cooling (unless you are in the middle of a desert and have a hot running engine). That brings up a different aspect; make sure your overall cooling system in in good shape (I think you say 'good nic'?).

As for the temp sensors. There may be three of them; one to feed the dash displays (somewhere on the head), one for coolant temp that feeds info to the ECU (usually on the t-stat housing), and the "Temperature-Time Switch". That last one looks bigger and acts like the "choke" on a carb. It tells the ECU to add a rich mixture (cold start injector) when the engine is cold, but only for a brief time (hince temp and time). I believe the locations/positions for all of these has changed a few times over the years. Hopefully you can find some good pictures in the referenced links above. Also try searching Google Image. But finding the right T-stat housing will be a big help; you should get one that houses two of these three items. Leaving the last one on the existing hole in the head (don't get it confused with the oil pressure switch - looks the same as the temp switch). In a real bind, you could eliminate the temp sender for the dash display and use that hole in the head for the ECU coolant temp sensor. The temp gauge on the dash isn't very accurate nor reliable anyway. Naturally it would be preferred to be able to monitor your engine temp. A separate aftermarket gauge and sender might be best if you have to resort to this approach.

Oddly enough, this is one (maybe the only) example where there is a better supply of related parts in the US than in Europe. Pretty much everything other than the FI system is more available there. If there are specific parts you need (eg. the T-stat housing), then post a ad in the "for sale/wanted" part of the forum.
 
Thankyou JimD and Dr.jeff that is very helpful indeed, so in that case I will use a bosch pump to suck the fuel then, also i wont bother with the cooling fan and play it by ear,as for the injectors might just get them tested or renewed, also jim.d thanks for the picture of the ecu mounting thats great, and i enjoyed reading your post on your conversion, i must say iam super impressed on your project brilliant!!!.
Yes i do need a fi thermostat housing, so i will do a ad for it, you guys have been so helpful, thanks,john
 
John, I'm sure there must have been quite a few FI conversions covered in the past. Have you been able to find much on it with the 'search' function? I'll bet there are some more good threads with additional details like the one Jim did. They might offer more useful insights as well. But please ask if any more questions come up. Let us know how it goes.
 
Dr.Jeff said:
John, I'm sure there must have been quite a few FI conversions covered in the past. Have you been able to find much on it with the 'search' function? I'll bet there are some more good threads with additional details like the one Jim did. They might offer more useful insights as well. But please ask if any more questions come up. Let us know how it goes.
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There are not a lot of threads on FI conversions. It's not that no one has done the conversion, they just didnt document it.

I ran into many unexpected problems because I had no idea what i was getting into. It turns out it is more complicated to convert a 74-78X to FI. 79+ Xs are already using electronic ignition and have the proper acceleration pedal and cable combo. The accel pedal/cable issue is a real PITA.
 
Thanks Jim, I did not realize that. I know not too long ago there was a thread on converting from FI to a single carb, oddly enough. I'm surprised more haven't documented the conversion the other way.

John maybe you can post up more pictures and explanation as you go through the project.
 
Hi guys, yes i will document the details on the conversion,as it will help others, iam sure i can come up with a solution to the acceleration cable, that will be documented, and thankyou again to you both. john
 
jcstuckinmuck said:
Hi guys, yes i will document the details on the conversion,as it will help others, iam sure i can come up with a solution to the acceleration cable, that will be documented, and thankyou again to you both. john
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John,

If your 79 is like the carb'd 79's in the US. It will already have the proper accelerator cable and pedal. Fiat changed the cable and pedal set up in 79 when they went to the 1500 engine.
 
Some random thoughts about this conversion:

1. The FI-specific stat housing places the FI coolant temp sensor in the engine's "internal" coolant circuit. If you cannot acquire an FI-specific stat housing, it might be acceptable to modify the water pump coolant return tube with a bung sized to accept the FI coolant temp sensor. You'd probably want to position the bung so that when installed, the sensor is not too close to the exhaust manifold.

2. Have you acquired an FI specific cylinder head? If not, it would seem within the realm of the do-able to mimic the clearance porting used on the FI-specific cylinder head.

3. If you have acquired an FI-specific cylinder head, then it adds provision for the Thermo-Time Switch (TTS) that also lives in the engine's internal coolant circuit (like the FI coolant temp sensor) and runs the cold start injector and the Auxiliary Air Valve. However, if you don't have an FI specific head and don't have a place to install the TTS in the internal coolant circuit, it would be possible to accomplish those two functions manually with just a little bit of ingenuity.

To mimic the function of the AAV, you'd use the AAV nipples on the intake snorkel and plenum, properly sized generic hose, but instead of the stock AAV, you'd substitute a simple manual cable operated heater control valve. Rather than being manually operated, opening and closing to regulate hot coolant flow to/from a heater matrix, the valve would instead be manually opened and closed by you to regulate air flow to elevate cold idle speed. In a sense it would be very similar to a manual choke cable. I'm sure a suitable place could be found to mount the valve in the engine bay, and it shouldn't be too hard to run an operating cable inside the car.

To mimic the function of the cold start injector, you would simply install a momentary contact switch somewhere within reach of the driver, and wire it up to energize the cold start injector manually. The TTS activates the cold start injector for a variable time (between 1-8 seconds) at startup, dependent of course on engine coolant temp--the colder the coolant temp, the more it squirts. On the other hand there is such a thing as too much, and the circuit in the TTS also has a heating element acting on a bimetallic strip, which prevents the cold start injector from being energized after an extended period of cranking, which helps to prevent flooding. If doing this manually you would of course have to temper your use of the cold start injector
 
Post a pic of your accelerator cable issue. Is it at the engine end (valve cover) that you have difficulty with? Depending on what you have, it might be easy to convert. I have both types so I can offer some direct comparisons if needed.
 
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